Course:Phys341 2020/Theatre voice

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Human Voice

Talking Voice

By Wanshan Wendy Cen (Phys341 project, 2020)

The human vocal system consists of the lungs and the lower airway that move about to supply air pressure and airflow. The vocal cords in which vibration modulates the airflow and produces voice source and the vocal tract further modify the voice sources, thus create given output sounds.[1]

Fig.1. Construction of vocal cords (own work)

Structure of Vocal Cords

The vocal cords (vocal folds) are composed of twin infoldings of mucous membrane stretched horizontally across the larynx.[2]

The vocal cords see Figure 1, are located side by side in the larynx, just above the trachea. When we are silent, the vocal cords remain open and create an airway through which we breathe. When we speak, the air we exhale from our lungs is forced through the closed vocal cords and this leads them to vibrate. The vocal cords vibrate faster for higher-pitched sounds, slower for lower-pitched sounds.[3]

The larynx also referred to as the voice box, located on the top of the trachea. It’s about 2 inches long in adults and sits on top of the trachea in the neck and in front of the food pipe.[4] The human voice originates in the vibrations of the vocal cords in the larynx. As we take a deep breath in, we are able to fill up our lungs with air. The vocal cords open to let air pass through the larynx, into the trachea, and down to the lungs.

The trachea also referred to as the windpipe, which is the tube-like passageway in our throat for air. The trachea sits below the larynx and runs down behind the breastbone. As we breathe out, the air travels back up through our larynx, also referred to as the trachea. The trachea widens and lengthens with each time we breathe in and return to its resting size with each time we breathe out.

Voice Types

A voice type is a singing voice identified as having certain characteristics of vocal range, vocal weight, vocal timbre, and vocal transition points.[5] Females are typically divided into three groups: soprano, mezzo-soprano, and contralto; while males are usually divided into four groups: countertenor, tenor, baritone, and bass.

Adult males and females typically have different sizes of the vocal fold, it shows the male and female differentiation in larynx size. Adult male voices are lower-pitched and have larger vocal cords compared with the female, which normally be measured between 17 mm and 25 mm in length and the female vocal cords are between 12.5 mm and 17.5 mm in length.[1] Hence, male vocal cords are usually larger and thicker than females, which makes their voices naturally deeper and lower than females. We can simply change our voices by relaxing or tightening the vocal cords; such as moving our tongue, jaw, and changing the shape of our mouth.

Fig.2. The 5 primary singing vowels (own work)

Theatre Singing Voice

An Individual's singing styles are differentiated by the timbre of the voice. Vowel selection is important in differentiating between singing styles. The timbre of the voice, which is related to its frequency spectrum, is controlled by both the glottal voices and the vowel choices made by the singers.

In theatre singing, vocalists are encouraged to use consonants and vowels for clarity of diction. In spite of these, most singers usually appear to be less concerned with clear diction than with the variable vocalization made possible by sustained vowels. In simple words, vocalists like opera singers tend to use vowels to make songs appear better to the ears of the audience, so they pay less attention to the clarity of every single word while singing. Therefore, to tell if a singer can maintain the timbre across a range of pitches, it determines on the ability to control the vowel space.[6]

Singing Belting Range

Fig.3. vocal range in piano keys (own work)

In general, the average range for both male and female singers is about two octaves; it could be a little bit more by a tone or a semitone, it varies on the person.

The vocal range of classical performance covers about five octaves, from a low G1 to a high G6.[5]

Among males, the broad categories of vocal ranges are bass (about E2-F4), baritone (about G2-A4), and tenor (about B2-C5).

Among females, the broad categories of vocal ranges are alto (about F3-A5), soprano (about A3-C6), and with mezzo-soprano in between.

Frequency Levels

As shown in the graph, the fundamental frequency between speaking and singing voices are different. In figure 4, it demonstrates the power spectrum of a female speaking voice. In general, the voice spoke of an adult male will have a fundamental frequency from 85 to 180 Hz, and 165 to 255 Hz of an adult female.[8] To look at the peak of the sound spectrum, we can tell the most pronounced frequency is around 240-250 Hz and the sound pressure level is around -30 dB (p.s. audacity are not absolute, it depends upon an arbitrary baseline. We could not actually hear an absolute sound pressure levels of -30 dB).

On the other hand, figure 5 demonstrates the power spectrum of the famous male vocalist singing voice, the voice file is from the clip of Luciano Pavarotti sings "Nessun Dorma". Unlike the speaking voice, singing voice can cover a frequency range of 100 Hz to 8 kHz. Thus, the power spectrum of the singing voice depends on the singing styles, timbre of the voice, types of songs, and etc. To look at the peak of the sound spectrum, we can tell the most pronounced frequency is around 200 Hz and 2 kHz and the sound pressure level is -22 dB.

Fig.4. The power spectrum of female speaking voice (own work)
Fig.5. The power spectrum of male vocalist singing voice, voice file from Luciano Pavarotti sings "Nessun Dorma"[7] (own work)

Furthermore, as shown in the chart below, it demonstrates the result after exporting the power spectrum into the textfile format by using the sample size of 256. On the left-hand side is the female speaking voice, and on the right-hand side is the male vocalist singing voice, voice file from Luciano Pavarotti sings "Nussun Dorma". The text file shows a more precise number of the frequency and pressure levels.

Fig.6. Text file of the Power Spectrum (own work)

References

  1. Zhang, Zhaoyan. "Mechanics of human voice production and control." The journal of the acoustical society of America 140, no. 4 (2016): 2614-2635.
  2. https://www.sciencedaily.com/terms/vocal_folds.htm Retrieved 2020-03-25
  3. Vocal Cord Disorders, Harvard Health Publishing https://www.health.harvard.edu/a_to_z/vocal-cord-disorders-a-to-z Retrieved 2020-03-25
  4. https://www.cancerresearchuk.org/about-cancer/laryngeal-cancer/what-is-laryngeal-cancer Retrieved 2020-03-25
  5. Classifications of Human Voice https://courses.lumenlearning.com/musicappreciation_with_theory/chapter/introduction/ Retrieved 2020-03-25
  6. Titze, Ingo R., Lynn M. Maxfield, and Megan C. Walker. "A formant range profile for singers." Journal of Voice 31, no. 3 (2017): 382-e9.
  7. Warner Classics. “Luciano Pavarotti sings "Nessun dorma" from Turandot (The Three Tenors in Concert 1994).” YouTube video, 3:15. June 7, 2019. https://youtu.be/cWc7vYjgnTs
  8. https://www.seaindia.in/human-voice-frequency-range/ Retrieved 2020-03-25
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