Dear Vocalisters:
A series of posts have appeared in the last weeks regarding use of chest voice in various musical styles. To my knowledge, none of these posts have suggested that a particular kind of chest voice should be used in all musical styles but, instead, have become concerned with the use of chest voice as a proper vocal technique.
Chest voice occurs when the vocal fold muscles (vocalis muscles) are active and provide a resistance to the stretching action of the crico-thyroid muscles. The resultant tension between these muscle systems produces a phonated sound that is rich in harmonics and, when produced in the possible frequency range, a strong fundamental. Adjustments of the vocal resonating spaces (vocal tract) allow the singer to make tonal changes in this phonated sound but these resonance adjustments do not change the vocal fold structure that produces the phonated sound.
In contrast, in high voice the vocalis muscles are no longer active and the necessary resistance to the stretching actions of the crico-thyroid muscles is now provided by the vocal ligament which is near the surface of the vocal fold. In effect, the vocal folds muscles (vocalis) are no longer a part of the phonational structure of the voice. This produces a phonated sound at a higher frequency with a pronounced fundamental and a harmonic spectrum that, although complete in pattern, is necessarily more spread out because of the higher fundamental frequency that is present.
(Note: Because partials of the fundamental occur as increments of the fundamental, the higher the fundamental, the more space is present between each successive partial. It is for this reason that female voices have a more difficult time locking onto the correct overtone resonances for a given pitch as compared to male voices which have more partials available for the process as well as having partials that are closer together.)
As the singer moves from chest voice into high voice a transition must occur somewhere in the process such that the vocalis muscles will gradually reduce activity and the vocal ligament will assume the work previously done by the vocalis muscles. How this is accomplished and where it is accomplished is the basis of most of the differences in vocal techniques between various vocal styles and even within a given style but in different countries. In addition, modification of the resonance spaces or vocal tract can either assist or detract from the process of making this vocal fold adjustment. This is so because the acoustic properties of the sound in the vocal tract can provide a kind of acoustic support for the vocal folds throughout the transition range.
The area of transition from chest voice into head voice and back again has been given a multitude of names such as middle voice, passaggio, turn over area, mixed voice ( in all its various forms such as low mix, high mix, etc.) but regardless of the name the vocal function that must occur is basically the same.
Pneumatic pressure on the vocal folds (breath pressure) will also have a direct effect on the ability of the vocal mechanism to make the transition from chest voice to high voice. Even the best produced voice will find it more difficult to make a smooth transition from chest to high voice while singing loudly and a much more easy time of it while singing softly. If the particular singing style requires or assumes amplification, the singer is less likely to sing loudly and more easily able to make the transition between chest and head. If the particular singing style requires or assumes no amplification, such as in opera, the singer will find the transition from chest to high voice a much more challenging hurdle. There are many devices that have been developed by the acoustic singer to make this transition easier and one of them is to not use the lowest forms of chest voice within the particular aria or scene being performed. But this does not preclude the use of all forms of chest voice within the vocal scope of music theatre, including opera.
As singers and voice teachers we most often concern ourselves with techniques that work regardless of why they work. The danger in this approach is that it is possible to develop a technique that limits the vocal potential of the singer and does not address the vocal demands of a particular singing style. At its worst, this pragmatic approach to singing can even provide a technical solution which is contrary to the organic physical functioning of the vocal mechanism. -- Lloyd W. Hanson
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