A colleague of mine wrote to ask if I knew of any resources for a young student who wishes to understand fundamental vocal structure. The student does not have enough money to afford one of the books available and so I decided to write some basics for the student.
Structure of the Voice as Musical Instrument
- All instruments have a vibrator that excites the ambient air producing complex waves of sound that reach the human ear through the same air, like the strings of a violin or human lips combined with the mouthpiece of a trumpet or the material that covers the timpani. For us singers, it is the vocal folds. The short 2 minute video below gives a simple but accurate description of the vocal folds and their surroundings:
2. As the bow of the violin causes the strings to go into vibration, thereby exciting the air around it with a very specific pattern of disturbance (what we hear as the timbre–the specific sound quality of the instrument), so do the hammers of a piano on its strings and so does the compressed air from the lungs to the vocal folds. The actuator is the mechanism that causes the vibrator to go into oscillation to excite the ambient air. Because the lungs are attached to the diaphragm right below them, when the diaphragm descends as part of inhalation, it expands the lungs and causes outside air to fill them to achieve equilibrium between air pressure outside and inside the lungs. In inhalation, other muscles such as the external intercostals and levatori costali (rib levitators) stretch open the ribcage further and by extension the lungs that are attached to it for more air intake (what feels like a deeper breath). During exhalation, several muscles–including the core muscles attached to various parts of the ribcage–work to contract the ribcage and squeeze (compress) the air in the lungs. Together with the rise of the diaphragm, a strong compression occurs which pushes out used air (C02) which brings the mucosal surface of the vocal folds (called cover) into vibration. The specific pitch (called Fundamental Frequency or F0) depends on the shape of the vocal folds as a response to the singer’s desire to produce that specific pitch.
In other words, the process of singing is more or less automatic. So everyone can sing, providing s/he can conceive of a specific pitch on purpose and the vocal apparatus and hearing are unimpaired.
Running is also automatic. The quality of the stride and speed depends on the runner’s physical training and native physical conditioning as well as a clear desire to run with a certain form that is learned (consciously or unconsciously) and a clear desire for a certain speed dependent on the runner’s physical conditioning and training. Likewise, the quality of the sung pitch depends on the singer’s native vocal make-up and physical conditioning. How loud and how beautiful the tone is produced depend on the singer’s ability to conceive of the specific tone quality and the condition of the vocal folds, breathing apparatus and the resonator. Below is a simple explanation of breathing (explore Youtube for hundreds of clips on the breathing process, including some specifically related to singing!).
3. The resonator, which is the vocal tract (see yellow outline in the featured title picture of this blog post), is the space between the vocal folds and the edge of the mouth. It basically shapes and filters the original vibration of the vocal folds into a more refined version depending on the singer’s desire. That refined version of the tone usually occurs in the shape of a vowel. The vocal folds produce the desired Fundamental Frequency and its endless overtones. Every tone produced by any natural sound source (not electronic) will produce a natural series of overtones that relate to its fractions. For example if we cut the lowest string of the cello (the low C string) in half, that portion called the second partial would vibrate one octave higher than the original string. If the string were cut in thirds, that third partial would vibrate an octave and a fifth above the original string. And since those partials exist with the uncut original C-string, the overtones sound as well although much quieter than the fundamental frequency. There is a theory that singers who have difficulty matching pitch (the fundamental frequency) may have ears so sensitive that they hear the overtones more strongly than the fundamental frequency. Below a really fun video showing a simulation of the “raw vibration” of the vocal folds coupled with realistic shapes of the vocal tract relative to vowels:
The shape and size of the vocal tract–influenced by the opening of the mouth, the depth of the larynx, where the vocal folds are housed, the shape of the tongue and lips–determines which partials are strengthened, weakened or canceled out. A vowel is simply a shape of the vocal tract that influences certain specific partials to be accentuated. In an acoustic display of the voice, called spectrogram, the dominant peaks relate to the chosen vowel (vocal tract shape). Therefore, different vowels sung on the same pitch will have distinctly different spectrographic displays. Those displays are called the acoustic envelope.
A good technique is the singer’s ability to influence the actuator (breath), the vibrator (vocal folds) and resonator (vocal tract) at will to produce specifically the desired sound. Difficulties in singing may be related to A) the physical conditioning of the singer’s body, including strength and balance of the muscles of the larynx, the muscles of breathing and the muscles of the vocal tract, state of the vocal folds (whether flexible or stiff–related to disease such as allergies, GERD, a cold or dehydration by many different causes including alcoholic and caffeinated beverages or a lack of water intake B) underdeveloped proprioception (the ability to sense physical occurrences in the body) relative to singing and/or C) the singing of repertoire that is inappropriate (beyond the physical limits of the specific voice at that specific time).
This is a barebones explanation of the human voice in singing. The singer’s knowledge should increase beyond this basic information in order to have more refined control of the vocal instrument.
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© 20 April 2020