UBC Wiki - User contributions [en]

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-04-05T17:02:45Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] (also known as the kalimba) is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" (beads attached to the instrument's tines) to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the tines of the instrument vibrate, but if the mbira has a resonant box (i.e. has a sound hole), the vibration is resonated through it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that the resonant frequency of the tine is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations decay as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes have their own resonant frequencies. The resonant frequency of a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). A vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The resonant boxes of a mbira also have a sound hole to increase perceived the loudness of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound at lower frequencies is radiated from the air vibrating in the hole opening. This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref> The sound hole of the mbira (as with other instruments) is able to make lower frequencies seem louder due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of a resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines are still transferred into these solid mountings (these vibrations can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent. This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

To summarize, the hole in a mbira's resonant box makes lower frequencies appear louder by causing sound oscillations at the cavity that would not have occurred otherwise. External resonators make the sound appear louder by receiving the vibrations from the plucked instrument and amplifying them to the human ear.

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-04-05T16:49:18Z

ElliotSpilsbury: /* External Resonators */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] (also known as the kalimba) is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the tines of the instrument vibrate, but if the mbira has a resonant box (i.e. has a sound hole), the vibration is resonated through it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that the resonant frequency of the tine is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations decay as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes have their own resonant frequencies. The resonant frequency of a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The resonant boxes of a mbira also have a sound hole to increase perceived the loudness of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound at lower frequencies is radiated from the air vibrating in the hole opening. This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref> The sound hole of the mbira (as with other instruments) is able to make lower frequencies seem louder due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of a resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines are still transferred into these solid mountings (these vibrations can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent. This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

To summarize, the hole in a mbira's resonant box makes lower frequencies appear louder by causing sound oscillations at the cavity that would not have occurred otherwise. External resonators make the sound appear louder by receiving the vibrations from the plucked instrument and amplifying them to the human ear.

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-04-05T16:45:46Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] (also known as the kalimba) is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the tines of the instrument vibrate, but if the mbira has a resonant box (i.e. has a sound hole), the vibration is resonated through it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that the resonant frequency of the tine is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations decay as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes have their own resonant frequencies. The resonant frequency of a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The resonant boxes of a mbira also have a sound hole to increase perceived the loudness of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound at lower frequencies is radiated from the air vibrating in the hole opening. This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref> The sound hole of the mbira (as with other instruments) is able to make lower frequencies seem louder due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of a resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines are still transferred into these solid mountings (these vibrations can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

To summarize, the hole in a mbira's resonant box makes lower frequencies appear louder by causing sound oscillations at the cavity that would not have occurred otherwise. External resonators make the sound appear louder by receiving the vibrations from the plucked instrument and amplifying them to the human ear.

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-04-05T16:45:14Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] (also known as the kalimba) is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the tines of the instrument vibrate, but if the mbira has a resonant box (i.e. has a sound hole), the vibration is resonated through it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that the resonant frequency of the tine is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations decay as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes have their own resonant frequencies. The resonant frequency of a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The resonant boxes of a mbira also have a sound hole to increase perceived the loudness of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound at lower frequencies is radiated from the air vibrating in the hole opening. This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref> The sound hole of the mbira (as with other instruments) is able to make lower frequencies seem louder due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of a resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines are still transferred into these solid mountings (these vibrations can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

To summarize, the hole in a mbira's resonant box makes lower frequencies appear louder by causing sound oscillations at the cavity that would not have occurred otherwise. External resonators make the sound appear louder by receiving the vibrations from the plucked instrument and amplifying them to the human ear.

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-04-05T16:22:35Z

ElliotSpilsbury: /* How Mbira Resonant Boxes Work */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the tines of the instrument vibrate, but if the mbira has a resonant box (i.e. has a sound hole), the vibration is resonated through it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that the resonant frequency of the tine is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations decay as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes have their own resonant frequencies. The resonant frequency of a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The resonant boxes of a mbira also have a sound hole to increase perceived the loudness of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound at lower frequencies is radiated from the air vibrating in the hole opening. This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref> The sound hole of the mbira (as with other instruments) is able to make lower frequencies seem louder due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of a resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines are still transferred into these solid mountings (these vibrations can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

[Very good. Needs concluding para - CEW]

==References==
{{reflist}}

Course talk:PHYS341/Archive/2016wTerm2/Physics Behind Overtone Singing

2017-03-27T23:11:30Z

ElliotSpilsbury: Talk page autocreated when first thread was posted

Thread:Course talk:PHYS341/Physics Behind Overtone Singing/Peer review of your work

2017-03-27T23:11:30Z

ElliotSpilsbury: New thread: Peer review of your work

Hi there,

Your article is well-written thus far, and for the most part I found it to be informative, objective, and comprehensible. I found the structure of your article to be easily-understandable, as you start off with the basics (i.e. what overtone singing is) before moving into the techniques and scientific phenomenon of the matter.

I would suggest that for some of the descriptions you give regarding how overtone singing is achieved, you consider creating diagrams to help the reader visualize what it is that you are describing. For example, when you say that "adept overtone singers achieve the desired effect through altering the shape of the vocal tract", it may be helpful to include a visual representation of exactly what sorts of tract shapes produce certain sounds. You also state that "Singers will change the shape of their vocal tract in order to align the frequency of a formant with that of a harmonic, therefore causing the overtone to resonate more strongly and create a perceivable change", and your inclusion of links to the wikipedia pages for "formant" and "harmonic" was helpful, however I think that a more in-depth explanation of what it means to "align the frequency of a formant with that of a harmonic" would be even more beneficial.

Similarly, in the section about the scientific phenomenon in overtone singing, you state: "Studies have suggested that the distinct clarity and strength of the sung overtones are a result of Helmholtz resonance within the vocal tract". It might be worth elaborating on which studies you are referring to (if you refer to them at all in the article) and elaborating on exactly how Helmholtz resonance manifests itself in the vocal tract (this is another place where diagrams could be helpful).

In general I would suggest slightly lengthening each part of your article with more detailed descriptions of the scientific processes you are analyzing, as it will help your reader understand the ideas you are portraying in a more substantial way, and it will help bring your article's word count up to the 1000-word minimum.

Generally though, I think that this is a good draft and it is for the most part informative and digestible for the reader. Good work.

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-17T23:33:39Z

ElliotSpilsbury: /* External Resonators */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes contain resonant frequencies. The resonant frequency in a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of a resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines are still transferred into these solid mountings (these vibrations can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-17T23:31:34Z

ElliotSpilsbury: /* How Mbira Resonant Boxes Work */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the tines themselves, mbira resonant boxes contain resonant frequencies. The resonant frequency in a box is largely dependant its size; larger boxes have lower frequencies and smaller boxes have higher frequencies, and as such alto boxes often have a fundamental frequency of around 440 Hz [A] while treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

The sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. This eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-17T23:08:47Z

ElliotSpilsbury: /* Structure of a Mbira */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which is how they were traditionally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound and add resonance to its fundamental frequencies. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built-in sound hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd (or another type of bowl) <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand). <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which internal resonance boxes and external resonators affect the instrument's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-17T23:00:04Z

ElliotSpilsbury: /* Structure of a Mbira */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instrument's notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-17T22:59:49Z

ElliotSpilsbury: /* Structure of a Mbira */

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the tines and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-17T22:40:23Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification and resonance. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira's box.
__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-16T17:00:21Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

__TOC__
[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]
===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-16T07:42:03Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

__TOC__

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

The process by which a bowl resonator causes a mbira to be perceived as louder is similar to the way in which a tuning fork can be amplified (to the human ear) with a resonance tube. When the tuning fork is struck, the tines vibrate at their own natural frequency, impinging upon the opening of the resonance tube. As a result the air inside the resonance tube vibrates at the same frequency as the tuning fork, causing the perceived loudness to increase when the water level in the tube is adjusted to an appropriate air column length that matches the vibration frequency. A similar process is used in the case of a mbira is a resonator bowl: when the tines of the instrument are plucked, the vibrations force the bowl to vibrate at that frequency as well, creating what seems to be a louder resonance. <ref>The Physics Classroom. "Resonance." The Physics Classroom. The Physics Classroom, n.d. Web. 16 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-16T03:14:23Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

__TOC__

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent This is usually done by placing the mbira into a bowl-shaped container, traditionally a calabash gourd. <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-16T02:58:08Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

__TOC__

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead simply have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder and making lower frequencies more prominent <ref> Holdaway, Mark . "A Resonant Body." Kalimba Magic. Kalimba Magic, 23 June 2006. Web. 15 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-16T02:51:29Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

__TOC__

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have a fundamental frequenct around 440 Hz [A] and treble boxes often have a fundamental frequency of around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

===External Resonators===
Traditionally, mbiras have not been equipped with resonant boxes, but instead just have a solid flat board mounting with no sound hole. Because of the lack of resonant box, these sorts of mbiras tend to be quieter than those with resonant boxes. Despite this, the vibrations created from the plucking of the instrument's tines is still transferred into these solid mountings (which can be felt by the human hand). This vibrational energy can be transferred into other systems, thus making the sound louder.

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-16T02:14:14Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

__TOC__

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have around 440 Hz [A] and treble boxes often have around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-15T23:17:11Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 - Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have around 440 Hz [A] and treble boxes often have around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-15T23:16:29Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have around 440 Hz [A] and treble boxes often have around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png|thumb|Fig. 2 - Diagram of Helmholtz Resonance in a mbira]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

==References==
{{reflist}}

File:Mbira diagram.png

2017-03-15T23:15:42Z

ElliotSpilsbury: User created page with UploadWizard

=={{int:filedesc}}==
{{Information
|description={{en|1=Fig. 2 - Diagram of Helmholtz Resonance in a mbira}}
|date=2017-03-15 16:14:23
|source={{own}}
|author=[[User:ElliotSpilsbury|ElliotSpilsbury]]
|permission=
|other_versions=
}}

=={{int:license-header}}==
{{self|cc-by-sa-3.0}}

[[Category:Uploaded with UploadWizard]]

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-15T23:14:06Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have around 440 Hz [A] and treble boxes often have around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

[[File:Mbira diagram.png]]

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T06:48:13Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have around 440 Hz [A] and treble boxes often have around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions. This causes low-frequency oscillations in the sound that would not occur if it weren't for the sound hole. The lower the position of the air mode, the deeper the resonance. Additionally, the inclusion of an air hole in the instrument eliminates the need to thin out the mbira's wood to an extreme extent, as thinning the wood creates a deeper resonance, but can eventually crack the wood.<ref>Waltham, Chris. "Radiation Mechanism." UBC Wiki. University of British Columbia, 2016. Web. 13 Mar. 2017.</ref>

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T06:10:58Z

ElliotSpilsbury:

[[Category:PHYS341-2017|KalimbaResonator]]
<big><big><big>The Resonator of a Mbira</big></big></big>

The [https://en.wikipedia.org/wiki/Mbira mbira] is a [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instrument that is sometimes used with a [https://en.wikipedia.org/wiki/Resonator resonator] for amplification. In some cases, the mbira is placed into an external resonator, and in other cases the resonator is built into the mbira. Because these resonators can vary in size, shape, and placement, different sorts of resonators can vary the acoustics of the mbira that they are coupled with.

===Structure of a Mbira===
Like all [https://en.wikipedia.org/wiki/Lamellophone lamellophone] instruments, the mbira is constructed with multiple thin plates, each fixed at one end. These plates are set into vibration by an instrumentalist plucking the plate(s) with his or her thumbs. The plates of the mbira are made from a variety of different materials, including iron ore from rocks (which was how they were originally made), sofa springs, bicycle spokes and car seat springs <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. Traditionally Mbiras have been equipped with "buzzers" to accompany the notes defined by the plates themselves, however, many Western manufacturers have opted for a "cleaner" sound, thus eliminating the use of buzzers in some cases. On Hugh Tracey Kalimbas (the first mbiras to be sold in the Western world), removable beads are attached to the instrument's tines to create the distorted effect. <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>

[[File:Gourdmbira.jpeg|thumb|Fig.1 Mbira with a gourd resonant box.]]

Aside from the metal and the buzzers, which provide the instruments notes and distortion, respectively, it is common for Mbiras to be used with resonators to amplify the instrument's relatively quiet sound. Resonators can be built into the instrument or added externally, often depending on the material that the plates are mounted upon. There are a wide variety of body materials that the plates can be mounted on, including boxes, boards, and hollowed gourds <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. See figure 1 for an example of a mbira with gourd mounting as a resonant box. In the case of the board mountings, it is common for the lack of a built in sound-hole resonator to be compensated for by attaching the instrument to an external resonator made from a calabash gourd <ref>Azim, Erica. "The Mbira Instrument ." MBIRA. MBIRA, n.d. Web. 6 Mar. 2017.</ref>. In most cases, built-in resonators are simply holes in the hollowed-out body (which can be used to manipulate the resonant properties of the cavity when someone covers it with their hand, and are often used with external resonators as well), but resonators can also be placed as a frame around the body of the mbira <ref>Holdaway, Mark. "WHAT ARE SOME OF THE FEATURES MY KALIMBA COULD HAVE?" Kalimba Magic. Kalimba Magic, n.d. Web. 6 Mar. 2017.</ref>. The purpose of this article is to explain the ways in which different sorts of resonators can affect the frequency of the mbira's sound.

===How Mbira Resonant Boxes Work===
When a Mbira is plucked on its own, the vibration lives on the tines of the instrument, but if the mbira has a resonant box (i.e. has a sound hole), the vibration lives in it as well. For around 0.05 seconds, discordant frequencies known as the note's "attack phase" can be heard as the tines initially vibrate. After the attack phase, the energy in the vibration organizes itself so that a resonant frequency is heard by the human ear, and the vibration energy begins to move back and forth between the the bridge mechanism holding the tines in place and the end of the tine. In most cases, these vibrations destroy themselves as they bounce back and forth (although this is not the case at certain self-sustaining frequencies). <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

Along with the plates themselves, the mbira resonant box itself contains resonant frequencies. The resonant frequency in a box is largely dependant on the box's size; larger boxes have lower frequencies and smaller boxes have higher frequencies (alto boxes often have around 440 Hz [A] and treble boxes often have around 490-520 Hz [B - C]). In any case, a vibration's frequency is inversely related to the vibration's wavelength, and if the wavelength is doubled, the frequency is divided half, and ultimately a lower pitch is perceived. <ref>Holdaway, Mark. "Resonance." Kalimba Magic. Kalimba Magic, 6 Oct. 2006. Web. 8 Mar. 2017.</ref>

The resonant boxes of a mbira also notably have a sound hole to increase the loudness and resonance of what's being played on the instrument. As with other instruments that use sound holes for resonance ([https://en.wikipedia.org/wiki/Guitar guitars], for example), the sound hole is used to lower the lowest frequency of the instrument without having to thin out the resonant box to an extreme extent. The sound radiation at lower frequencies in the instrument is enhanced as the air vibrates near the box's opening (as well as inside the box itself). This process is known as [https://en.wikipedia.org/wiki/Helmholtz_resonance Helmholtz resonance], and it is often observed in sound in empty bottles as air is blown over the top of the opening, as can be seen in Fig. 2. <ref>Berkeley. "Acoustics of Sound-holes in Musical Instruments." Theoretical & Applied Fluid Dynamics Laboratory. TAF LAB, 2017. Web. 13 Mar. 2017.</ref>

It is also worth noting that the sound hole of the mbira (as with other instruments) is able to make lower frequencies resonate more largely due to the fact that the air inside the instrument's body and the sound hole are moving in opposite directions.

==References==
{{reflist}}

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T05:35:18Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T05:31:02Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T04:45:38Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T04:35:00Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T04:32:15Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T04:30:32Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T04:14:30Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T03:51:17Z

ElliotSpilsbury:

File:Gourdmbira.jpeg

2017-03-14T03:50:41Z

ElliotSpilsbury: User created page with UploadWizard

=={{int:filedesc}}==
{{Information
|description={{en|1=Mbira with a gourd resonant box.}}
|date=2017-03-13 20:04:32
|source={{own}}
|author=[[User:ElliotSpilsbury|ElliotSpilsbury]]
|permission=
|other_versions=
}}

=={{int:license-header}}==
{{self|cc-by-sa-3.0}}

[[Category:Uploaded with UploadWizard]]

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T03:49:01Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-14T03:46:29Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-09T05:27:36Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-09T05:25:37Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-08T10:34:00Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-08T02:05:28Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-08T01:57:40Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-08T01:55:55Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-08T01:41:41Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T08:16:57Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T08:02:58Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T07:57:41Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T07:56:03Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T07:45:31Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T07:33:20Z

ElliotSpilsbury:

Course:PHYS341/Archive/2016wTerm2/KalimbaResonator

2017-03-07T07:32:22Z

ElliotSpilsbury: