The Human Voice


The human voice is a dynamic instrument. It's also the very first musical instrument that ever existed on Earth. Its ability to articulate, communicate ideas, create beautiful melodies, and translate human emotion into sounds is unmatched in the animal kingdom. In this article we are going to go into some of the interesting ways the human voice is used and can be manipulated by its user to bring about a desired artistic outcome. I will also relate some of the information we'll discuss here to other ideas I've talked about in previous articles about tuning musical instruments to frequencies outside of the Equal-Temperament system. Because the human voice is a self-tuning instrument, in that it doesn't require knobs or other tools to change its tone or timbre, it's one of the easiest of all instruments to relate to the subject of microtonal music. It's also very important to relate it to microtonal music because, like the fretless bass or a violin, it's one of the few instruments which can access microtones by sliding across and between the notes of the Equal-Temperament system of tones. In a previous article I wrote, "so since any frequency can be considered a note so long as it's assigned a letter name or some other designation, and a scale is any set of allowable notes used in a composition, then any instrument, including the human voice, can be tuned or modulated to access the sonic material found only in microtonal music." Physiology: What Makes a Voice Unique? The sound of each individual's voice is entirely unique. Its uniqueness is due to the actual shape and size of an individual's vocal cords as well as the size and shape of the rest of that person's body, especially the chest and vocal tract. The manner in which the speech sounds are habitually formed and articulated adds another set of factors that determines vocal character. (It is this latter aspect of the sound of the voice that can be mimicked by skilled imitators.) Human spoken language makes use of the ability of the vocal cords to dynamically modulate themselves within certain parameters in a socially consistent manner. The most important communicative, or phonetic, parameters are the voice pitch (determined by the vibratory frequency of the vocal folds) and the degree of separation of the vocal folds.

Children learn to use all of these actions consistently during speech development. They learn to speak the difference between utterances by listening to and imitating the voices of the adults around them. They mimic these voices playfully because they are so much different from their own. Humans have vocal folds that can loosen, tighten, or change their thickness, and over which breath can be transferred at varying pressures. The shape of the chest and neck, the position of the tongue, and the tightness of otherwise unrelated muscles can be altered to give the voice a certain quality. Any one of these actions results in a change in pitch, volume, timbre, or tone of the sound produced. Sound also resonates within different parts of the body, and an individual's size and bone structure can affect to a certain degree the sound produced by an individual.

Adult men and women have different sizes of vocal fold which reflects the male-female differences in larynx size. Adult male voices are usually lower-pitched and have larger folds and the female vocal folds are smaller - between 12.5 mm and 17.5 mm in length. The folds in both sexes are within the larynx. The folds are located just above the vertebrate trachea (the windpipe, which travels from the lungs). The difference in vocal folds size between men and women vary as well because of genetics causing men and women's singing voices to being categorized into types. For example, among men, there are bass, baritone, tenor and countertenor (ranging from E2 to even F6), and among women, contralto, mezzo-soprano and soprano (ranging from F3 to C6). There are additional categories for operatic voices.

Basic Mechanics: The World's First Human Instrument

Singers use the human voice as an instrument for creating music. The vocal folds, in combination with the articulators, are capable of producing a highly intricate array of sound. The tone of voice may be modulated to suggest emotions such as anger, surprise, or happiness. Singers can also learn to project sound in certain ways so that it resonates better within their vocal tract. This is known as vocal resonation.

Vocal resonationis the process by which the basic product of phonation is enhanced in timbre, amplification, enrichment, enlargement, improvement, intensification, and prolongation. The end result of resonation is, or should be, to make a better sound. Or from my point of view to control sound better. There are seven areas along the path of air which leaves the body to produce a musical sound that are vocal resonators. In sequence from the lowest within the body to the highest, these areas are the chest, the tracheal tree, the larynx itself, the pharynx, the oral cavity, the nasal cavity, and the sinuses.

Another major influence on vocal sound and production is the function of the larynx, which people can manipulate in different ways to produce different sounds (think ventriloquists and imitators). The primary method for singers to accomplish this is through the use of the Singer's Formant, which is a resonance added to the normal resonances of the vocal tract enabling the singer's voice to carry better over musical accompaniment. These different kinds of laryngeal function are described as different kinds of vocal registers.

Vocal registration refers to the system of vocal registers within the human voice. A register in the human voice is a particular series of tones, produced in the same vibratory pattern of the vocal folds, and possessing the same quality. Registers originate in laryngeal functioning. They occur because the vocal folds are capable of producing several different vibratory patterns. Each of these vibratory patterns appears within a particular vocal range - consisting of a range of pitches - and produces certain characteristic sounds. The term register can also be used to refer to any of the following:

A part of the vocal range such as the upper, middle, or lower registers.

A resonance area such as chest voice or head voice.

A vocal timbre.

A region of the voice defined by vocal breaks.

A subset of language used for a specific purpose or in a particular social setting.

The Human Voice is a Microtonal Instrument: Counter-argument

According to a study published by the New Scientist, the twelve-tone musical scale, upon which some of the music in the world is based, may have its roots in the sound of the human voice during the course of evolution. Analysis of recorded speech samples found peaks in acoustic energy that mirrored the distances between notes in the twelve-tone scale.

In alignment with the previous statement, the only rational argument opposed to the idea that the human voice is a microtonal instrument comes from the thinkers at the Schiller Institute. The first point they make is that middle C must be set at the frequency 256 Hz. Why? Because the human voice shifts registers at key points of the musical scale when C=256. Currently, middle C is set to the frequency 261.63 Hz. This small alteration in the placement of middle C forces the human voice to strain at shifting registers at awkward places in the musical scale, thereby precipitating injury to the vocal cords. Instead, what theorists at the Schiller Institute suggests is that when C = 256, the human voice lines up perfectly with the musical scale in significant locations - specifically at the tri-tone and the half-steps in the musical scale. Instead what the Schiller Institute argues is that the voice should be mirroring in vocal registration the musical scale itself.

Although their thinking is well grounded in facts about the human voice, the one aspect of their position that irks me is how they are essentially arguing for a new tuning system to replace Equal-Temperament, where C=256. That they actually want another fixed standard where another set of 12 frequencies is all that comprise music and song is certainly bothersome.

Conclusion: The Human Voice is a Microtonal Instrument

The physiology and the basic mechanics of the human voice essentially determine that it is a microtonal instrument. Its ability to produce frequencies ranges from about 60 to 7000 Hz with the ability to produce every single frequency and tone within that range.

Marc Avante is a musician, sound designer, and blogger. He is also the founder of the music project called Stereo Thesis. Stereo Thesis is a prototype sound design and music studio.
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