Altering the Timbre of a Trumpet
By Ethan Snyder and Juan Pablo Saa
Introduction
The timbre of a trumpet can be altered in a variety of different ways. That said, in this article, we will mainly focus on mutes and how these are able to change the timbre of a trumpet’s sound wave. Having said that, before delving into our topic, we must first give some background information on trumpets and how they work, as well as explain some key concepts such as “timbre” and “mutes.”
What is a Trumpet?
Trumpets are brass instruments that are frequently used by jazz ensembles, classical orchestras, and bands of all sorts. Even though there is a wide variety of trumpets, the most common one is pitched in B♭ and has a tubing length of approximately 1.48 meters. That said, it must be mentioned that a trumpet’s tubing is never straight, but bent twice in order to create a rounded rectangular shape (Koehler).
Trumpets are “transposing instruments” which, according to the Encyclopedia Britannica, are “instruments that produce higher or lower pitches than those indicated in the music written for them.” That said, a trumpet’s pitch will vary depending on the type of trumpet that is being used (Encyclopædia Britannica). For instance, the piccolo trumpet (the instrument with the highest register in the entire brass family) has a pitch that is one octave higher than a standard B♭ trumpet. On the other hand, the bass trumpet (the trumpet with the lowest register) has a pitch that is one octave lower than a standard B♭ trumpet (Danzmayr).
A Brief History of the Trumpet
Throughout history, instruments similar to trumpets have been used during battles or while hunting as signaling devices. In fact, examples of trumpet-like instruments date all the way back to 1500 BC. However, it was only in the late XIV century and the early XV century that they started being used as musical instruments. It was also at this time that they started being made primarily out of brass. That said, it must be highlighted that the incorporation of valves (allowing users to change the length of a trumpet’s tubing and therefore, its pitch) only happened in the year 1820. Before then, the only way to alter a trumpet’s pitch was by tightening or relaxing one’s lips (The New Harvard Dictionary of Music).
Nowadays, trumpets have three or (in some cases) even four valves, allowing users to change the instrument’s tubing length (and pitch) without having to change the position or shape of their lips. On top of that, it must also be mentioned that while modern trumpets tend to have valves of the piston type, those made specifically for orchestral settings can have valves of the rotary type (Koehler).
The Physics of Trumpets
Sound waves are created through vibrations. When it comes to trumpet sounds, these happen due to the high-speed vibrations produced by a player’s lips. While some might think that blowing into a trumpet’s mouthpiece is what produces sounds, this is not the case. In fact, musicians only blow into a trumpet because doing so makes their nearly-closed lips (known as a player’s “embouchure”) buzz/vibrate. Similarly, according to Mackenzie Stamey from the University of Alaska Fairbanks, “The mouthpiece simply gives the lips a place to vibrate, and harnesses the vibrations” (Stamey).
The vibrations that are harnessed in the mouthpiece then create a sound wave that travels down the tubing, until it reaches the trumpet’s flared bell. Acting as a node, the bell causes the wave to go back to the mouthpiece, effectively creating a standing wave vibration within the instrument. Some of the vibrating energy is released in the form of sound, thus creating the sounds we hear coming out of a trumpet (Luther High School).
What is Timbre?
Now, it must be mentioned that trumpet sounds (as well as all other sounds) have three different properties: loudness, pitch, and timbre. Loudness is associated with a sound wave’s amplitude, pitch is associated with its frequency, and timbre is associated with its shape (Towell). Timbre is the characteristic waveform of each sound; It depends on the “material” that produces it, and it is thanks to this property that we can differentiate between two sounds with the same loudness and frequency (Toppr).
How to Alter a Trumpet's Timbre
Even though sounds produced by the same instrument have similar timbres (all soundwaves produced by trumpets have relatively similar shapes), there are ways to alter these soundwaves, and therefore, their timbres. When it comes to the trumpet, there are a wide variety of factors that can alter its timbre. That said, for the sake of brevity, we will only focus on one of these: the use of mutes.
Mouthpieces
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When it comes to the factor of mouthpieces, we recorded the sound waves produced by a trumpet using 3 different samples (Bach 3C , Fbesson #4, and Olds 3). When taking these measurements, we made sure to keep everything the same, except for the mouthpiece being used. The loudness, pitch, embouchure, microphone, room size, temperature, and distance to the microphone were all the same. The comparison between the soundwaves recorded using 3 different mouthpieces can be seen in image 2.
Coating
Even though we considered other factors (such as mouthpieces, and a trumpet’s coating), we have determined that we don’t have the technology required to demonstrate that these do alter a trumpet’s timbre. Despite the fact that we did record the sound waves produced by three different mouthpieces, and by two different trumpets with different coatings, we don’t believe we can confidently claim that these factors were single handedly responsible for the changes that can be seen in the different soundwaves.
Even though at a first glance it might appear that the mouthpieces did change the soundwave’s timbre (after all, there are some slight variations in the overall shapes of the waves), we aren’t able to say for sure that these variations were singlehandedly caused by the difference in mouthpiece. After all, the variations present in these soundwaves are nothing out of the ordinary.
As a control, we recorded three different soundwaves produced by the exact same trumpet. Even though we believed that these soundwaves would be virtually identical, this wasn’t the case. In fact, there were slight variations in their respective timbres, something that can be seen in image 7. When comparing the soundwaves produced by 3 different mouthpieces to those recorded in our control, we don’t see any noticeable difference. Therefore, with the rudimentary technology we currently possess, we aren’t able to prove that the use of different mouthpieces alters a trumpet’s timbre, even though that might very well be the case.
The same goes for the factor of coating. We recorded the sound waves produced by two different trumpets with different coatings (silver-plated, and raw brass) under the same circumstances that were previously mentioned. Even though there were slight variations in the soundwaves produced by these trumpets (see image 2), these variations weren’t dissimilar to those that could be found in our control.
Considering this, even though factors such as mouthpieces and coating might alter a trumpet’s timbre, we have decided to focus solely on the factor of mutes. After all, the variations in the soundwaves produced by trumpets with different mutes are significant, noticeable, and irrefutably out of the ordinary.
What is a Mute?
Mutes are used by brass players to reduce the volume and/or timbre of their instrument. They can be placed directly into the bell of the instrument, be held, or clipped on. Mutes are used in many different kinds of music, but jazz often calls for the most variety. Among the varieties of mutes, different sizes are used by different instruments depending on the size of the bell.
There are many different kinds of mutes that all serve different purposes, but among the most common are straight mutes, harmon mutes, plungers, cup mutes, bucket mutes, and practice mutes. We chose to look at how straight, harmon, and a plunger can affect the timbre of a trumpet as these are the mutes we had available to us.
Physics of Mutes
While they look very different to traditional instruments, mutes alter the sound an instrument makes by using similar principles to instruments. A mute will have certain ways they vibrate as well as ways that the air inside of them can vibrate. Energy from the sound coming out of an instrument is altered by the ways that an mute and the air inside of them can vibrate, hence creating different sounds. The size and shape of mutes can be altered to produce a desired sound.
Measurements
To look at changes in timbre, we used Audacity as well as Friture to measure the sound wave over time and compared the different recordings. We used the trumpet note C (concert B♭), which is approximately 233 Hz. We kept this the same to ensure that the timbre of the note will not be influenced by the pitch that is played. A Rode NT USB mini microphone was used, as it was the highest quality microphone we had at our disposal. We used the highest quality of microphone at our disposal to ensure that differences we saw in timbre were due to actual differences and not poor measurements.
Audacity measures sound over time and plots data points to create a wave that can be played back through a speaker to recreate the original sound. The variations in the graph from a pure sine wave are what produce different timbres. By comparing these waves we can look at how timbre is changed based on the muste that is used. Friture is a similar program, but it also allows us to look at the intensity of different frequencies. In our case, we used it to look at how different harmonics may have been altered by different mutes.
Data
Unaltered
As stated above, we determined that we would be unable to measure differences in timbre based on the material of the instrument. The following graph shows the same trumpet using the same mouthpiece playing the same note was able to produce three noticibly different time graphs. It is important to note, just because we were not able to measure a difference in timbre between the plating of an instrument or mouthpieces, this does not mean there is not difference in timbre, just that we were unable to state with confidence the differences based on the time graphs were created.
Harmon (With and Without Stem)
We begin with the harmon mute. There are two ways to use a harmon mute, with and without the stem. While multiple samples showed differences in timbre when all other factors are kept constant, the difference in timbre when using a mute is significant enough that comparisons can be made with only one sample. The first difference between the harmon mute and no mute is the amplitude of the sound waves. This corresponds with one of the primary uses of mutes, which is to reduce the volume of sound. The next noticeable difference is the shape of the graph. Almost all distinguishable peaks and valleys of a trumpet without a mute are lost when a harmon mute is used. The wave becomes much smoother, with the amplitude of the wave changing more than the shape.
When the stem is removed, the changes become even more pronounced. Little can be seen in terms of a sine wave, the graph is periodic, but the amplitudes are so small that almost all distinguishable features except the initial peak is lost. Getting a measurement of the harmon without a stem was challenging as it reduced the volume so much and caused the sound to have little directionality.. This made it challenging for the microphone to record it.
We also took a Friture measurement of all of the mutes to compare with no mutes, and for all of the mutes except the harmon, the only noticeable difference was that the amplitude of all of the frequencies was reduced. The exception to this was the harmon mute with the stem. In this case, many of the lower frequencies, including the fundamental, were suppressed, allowing higher fundamentals to be more audible.
Straight
Next, we created a time graph for a straight mute. This difference in timbre here is less pronounced than with a harmon mute. Many of the tallest peaks and valleys have been smoothed out and decreased in amplitude. A straight mute changes the timbre of a trumpet less than a harmon mute does. It makes sense that the straight mute has the least effect on the timbre, as the sound it produces is most similar to an unaltered trumpet and a harmon mute almost sounds like another instrument.
Plunger
Finally, moving on to the plunder. As this is simply an ordinary plunger, it is possible to create an airtight seal between the mute and the instrument. Also, plungers are often used dynamically to create interesting sounds in music. This would make it hard to compare as it would be the only dynamic mute used, so the mute was used statically and by obscuring as much of the bell as possible. As is shown in the graph, this effect was similar to the straight mute, where the major peaks and valleys of the time graph were smoothed out, as well as the amplitude decreasing. The effect with the plunger was much more pronounced than the straight mute, but it makes sense that they did similar things as neither dramatically changes the timber of the trumpet like the harmon does.
Conclusion
Since their inception, trumpets have continued to evolve to provide musicians with more opportunities to control the sounds they create for better and more enjoyable music. From different coatings to keys there are many ways that trumpets have evolved over the years. Throughout all of the evolution, mutes have constantly provided ways to alter the timbre of trumpets. While we initially hoped to use the plating of the instrument, differences in mouthpieces, and mute in our comparison of timbre, this was not possible. Between individual variability between measurements and a lack of fidelity of our tools, we opted to focus on how mutes affect timbre, as they have a greater effect. While by just listening to how different mutes affect the sound of a trumpet, you may be able to make a guess about which alters the timbre the most, but in this investigation we are able to use measurements to clearly see differences in timbre and describe them beyond simply our senses.
Works Cited
- Danzmayr, David. “The Brass Family.” Brass Family of Instruments: What Instruments Are in the Brass Family?, https://www.orsymphony.org/learning-community/instruments/brass/.
- Encyclopædia Britannica. “Transposing Musical Instrument.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., https://www.britannica.com/art/transposing-musical-instrument.
- Koehler, Elisa. Dictionary for the Modern Trumpet Player. Rowman & Littlefield, 2015.
- Luther High School. Trumpet. https://lutherhigh.org/documents/arts/les_band/instrument_info/trumpet_info.pdf.
- The New Harvard Dictionary of Music. “History of the Trumpet.” History of the Trumpet, https://web.archive.org/web/20080608095025/http://www.petrouska.com/historyofthetrumpet.htm.
- Sam, & Sam. (2020, December 26). Anatomy of a trumpet - what are the main parts of a trumpet. Merely Music. Retrieved April 10, 2023, from https://merelymusic.com/anatomy-of-a-trumpet/
- Stamey, Mackenzie. “General Physics of the Trumpet.” University of Alaska Fairbanks, 5 Nov. 2013, http://ffden-2.phys.uaf.edu/211_fall2013.web.dir/Mackenzie_stamey/4General-Physics.htm.
- Toppr. “Timbre: Definition of Timbre, Theory, Characteristics, Examples.” Timbre, https://www.toppr.com/guides/physics/sound/timbre/.
- Towell, Gayle. “Pitch Definition (Physics): Understanding Frequency of Sound.” Sciencing, 29 Apr. 2021, https://sciencing.com/pitch-definition-physics-understanding-frequency-of-sound-13722355.html.
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