The writers of the master songs of church counterpoint utilized the head tones of men in their works. We have the careful account of Cerone (1613) on this matter, and he recognized two registers— chest and head. Since, therefore, the head voice (so-called) has been known and systematically used since the earliest period of the art of singing, we may accept it as a demonstrated fact.
The name is not quite satisfactory; but few of the terms used in the practice of singing are. This expression, “head voice,” simply means that the notes in its range seem to cause vibrations in the skull or some part of it, whereas the physical feeling of vibration in the medium register is in the pharynx and in the lowest tones in the upper part of the chest.
Here we are again confronted with an inexact terminology. Most masters of singing divide registers into three — chest, medium and head. Very few of them hold that there is any change of mechanical operation in the passage from the chest to the medium. They are speaking merely of division of the scale. For practical purposes, it is convenient to use the three terms, but their true meaning must never be forgotten.
Sir Morell Mackenzie made many careful experiments and laryngoscopic investigations into this subject, and exhaustively reviewed the work of leading scientists and teachers. His conclusion, while it may not be that accepted by all the best contemporaneous masters of singing, is nevertheless worthy of serious attention. He found just the same number of registers as Caccini found three centuries ago — namely, a chest and a head.
In the chest register the pitch of the tones is raised, according to Mackenzie, by an increase of the tension of the vocal cords, and also by an almost microscopic addition to their length. In the head register, the pitch is raised by a gradual shortening of the vibrating reed, which is not quite so tense as in the chest register.
In other words, when the pitch has been raised as far as possible by an increase of tension on the vocal cords, the mechanical process is altered, and additional notes can be obtained by a different method. In producing these additional notes the vocal cords relax a trifle and then substitute for vibrations involving their entire length vibrations of only a part of it.
The cords come together just as they do in the natural lower tones, and then a small aperture near one end opens and allows itself to be set in vibration by the air blast. This produces the head tones, and the problem of the singer is to learn how to pass from the lower register into this one without so great a change in the quality of the voice as to cause a shock to the sensitive ear.
Mackenzie calls attention to the fact that all the scientific investigators of the voice have found only two registers. He names Müller, Mandl, Battaille, Vacher, Koch, Meyer, Gougenheim and Lermoyez. Teachers of singing, on the other hand, have almost always held that there are at least three registers, and some of them have discovered as many as five. These five cannot be anything more than arbitrary divisions of the scale. There are not four changes in the anatomical process of voice production. There is only one, and that is the one which takes place at the transition from the “voce piena” to the “voce finta.”
Henderson, William James. The art of singing. Da Capo Press, 1978.