Frank E. Miller

PITCH AND SYMPATHETIC VIBRATION

It is sympathetic vibration, manifesting itself in some instances in the chest and in the head cavities, and in other instances almost entirely within the latter, that gives to voices their peculiar timbre or tone-quality—their physiognomy. It is by timbre that we distinguish voices as we distinguish features. With instruments, differences in quality of tone—differences in timbre—are due to differences of shape; and in case of instruments of the same kind, for example, violins, to slight differences in form or to the grain, age and quality of the wood. In the same manner, there are minute differences in the structure of the vocal tract of different people; and it is especially the structural differences between the resonant cavities of individual singers that determine differences of timbre or quality. It is easy to distinguish between tones even of the same pitch that come from a harp, a violin, a trumpet, a flute or from the human voice. Between two violins of exactly the same make, played on by the same person, there would be greater difficulty in discovering differences in the quality of tone, although, even if made after the same pattern and about the same date, there probably would be minute structural differences that would differentiate their timbre to a musical ear; while if, of two violins, one of the instruments were new, and the other old, a musical ear probably would immediately detect differences in their tone-quality.

It is easier to distinguish between voices even of the same range, than between instruments of the same kind, because there is strong individuality in voices. This is due to the fact that structural differences between the vocal tracts of individuals are far more numerous and far more minute than possibly can be introduced into instruments. Moreover, the vocal tract, being part of the human body, is subtly responsive to innumerable impulses and adjusts and readjusts itself in innumerable ways. Instruments are made of material, chiefly wood and metal, and, unlike the vocal tract, cannot change structurally. The cornet, for example, is made of brass. The lips of the player protruding into the cup can effect certain changes in shape, and changes also can be made in the tube between the mouthpiece and the bell of the instrument by pistons or valves. But these changes are absurdly small in number compared with the structural changes of which the vocal tract is capable, and commonplace in character compared with the refined and subtle minuteness of the latter. For this reason, while there is a distinct timbre for each kind of instrument, there are innumerable timbres of the human voice—as many as there are voices, and all due to the pliability of the vocal tract.

It is the manner in which the numerous individual conformations of the vocal tract affect the overtones in the voice that makes voices different from each other; for the overtones are the chief agency in determining the timbre, quality, or physiognomy of any tone. Every tone consists of a fundamental or ground tone with its overtones. The fundamental tone determines the pitch; the overtones determine the quality, tone-color, timbre, or physiognomy of the tone.

The overtones, or harmonics, as they also are called, vibrate in certain simple harmonic relations with the fundamental—from twice to five times as often per second, sounding the octave above, the fifth of that octave, the second octave, the major third of that octave, etc. So important is it to the individual musical quality of tone, to secure the coÖperation of overtones, that in certain large open organ pipes, which are deficient in these, extra pipes of higher pitch and corresponding with the overtones of the fundamental note, are added and joined to the register. Overtones without the fundamental can be obtained on stringed instruments by stopping one of the strings and then touching it lightly at other points. The soft, sweet, ethereal character of the harmonics produced in this manner on a violin conveys some idea of the manner in which the many overtones of a note give it its distinctive quality.

In a way the overtones may be said to echo the fundamental, but the ear receives fundamental and overtones blended as one tone of a certain timbre. What that timbre is, is determined by the shape of the resonating cavity or cavities, the shape of which in turn is determined by the shape of the instrument, and in different voices by infinitesimal differences in the shape of various parts of the vocal tract. All instruments of a kind are made more or less on the same pattern and vary but little in shape. For this reason we have the distinct violin, horn, clarinet or pianoforte timbre, and so on down the list, but I repeat here that there are not such minute and individual differences between instruments of the same kind as there are between voices of the same range, because there are no such minute and individual structural differences in instruments as in the vocal organs of individuals—differences that each individual can multiply ad infinitum by the subtle and delicate play of muscles acting in response to mental suggestion, art sense, inspiration, temperament, psychic impulse, or by whatever cognate term one may choose to call it.

There is little or nothing of psychology in Mackenzie's book, and yet, like other writers on voice-production, he appears now and then to be groping for it. Thus, when he speaks of the fundamental tone being reinforced by its overtones—by a number of secondary sounds higher in pitch and fainter in intensity—he adds very beautifully that every resonance-cavity has what may be called its elective affinity, or one particular note, to the vibrations of which it responds sympathetically like a lover's heart answering that of his beloved. "As the crude tone issues from the larynx, the mouth, tongue and soft palate, moulding themselves by the most delicately adaptive movements into every conceivable variety of shape, clothe the raw bones of sound with body and living richness of tone. Each of the various resonance-chambers reËchoes its corresponding tone, so that a single well-delivered note is, in reality, a full choir of harmonious sounds."

Voice being, like instrumental tone, a commixture of fundamental and overtones, and the manner in which the composite conformation of collective waves strikes the ear being largely determined by the cavities of resonance, the control of these is of great importance to the singer. This control should, by thorough training, be brought to such a degree of efficiency that it becomes subconscious and automatic, so that the resonance-cavities shape themselves instantly to the note that is being produced within the larynx and, vibrating in sympathy with it, sound the overtones. The reciprocal principle of elective affinity between fundamental and overtone, between the shape assumed by the larynx for pitch and the shape assumed by the resonance-cavities for quality, is illustrated by the exciting influence of a sounding instrument upon a silent one tuned to the same pitch which, although not touched by human hand, sounds in sympathy with the one that is being played on. Even a jar standing upon a mantel-shelf, a globe on a lamp, a glass on a table, or some other object in the room, may vibrate and rattle when a certain note is struck on the pianoforte. This is the result of sympathetic vibration. Thus, although vocal tone originates within the larynx, it sets the resonance-cavities into sympathetic vibration, and these produce the harmonics that give the fundamental tone its timbre; the resonance-cavities being to the vocal cords or lips what the body or resonance-box of the violin and the sounding-board of the pianoforte are to their strings, the tube of a cornet or horn to the lips, the body of the clarinet to its reed—the resonating factor which determines the overtones and through these the timbre.

Excepting the chest and trachea the resonance-cavities of the voice are located above the larynx. To the chest as a resonator the low tones of the voice owe much of their great volume. Indeed, the chest is such a superb and powerful resonating box that, if it resonated also for the high tones, these, with their inherent capacity for penetration, probably would become disagreeably acute. Therefore, nature, wise in this as in many other things, has decreased chest vibration as the voice ascends the scale.

Above the larynx is the pharynx, a space extending to the base of the skull and opening into the mouth, and higher up connecting with the base of the nose by means of two passages, the posterior nares, or back nasal passages. The walls of the pharynx are permeated by a network of muscles, so that this important space or resonance-cavity immediately above the larynx is susceptible of numerous adjustments and readjustments in size and shape; and as it lies with its back wall against the spinal column, it also is susceptible and immediately responsive to suggestion from the mind.

Another important resonance-cavity, indeed, the most important, is the mouth, roofed by the hard palate which separates the mouth from the nasal chamber, to which latter it also forms the floor. In the mouth is the tongue, extremely mobile, and thus capable of materially changing the size and shape of the mouth-cavity. Hanging from the rear of the hard palate, like a veil over the root of the tongue, is the soft palate; attached to which is the uvula. This hangs vertically down from the soft palate and, if the rear end of the tongue is allowed to bulge upward slightly, can be made to form with it a kind of valve, by which voice is conveyed directly into the mouth-cavity without any of it escaping up the posterior nasal passage; while the soft palate by itself alone can be drawn up so as to touch the back wall of the pharynx, completely closing the passage to the nose, so that a continuous curved resonance-cavity is afforded from larynx to lips.

The soft palate is continued on either side by two folds known as the fauces; and each of the fauces has two ridges, the pillars of the fauces, between which are the tonsils. The pillars of the fauces enclose muscular fibres which act respectively on the tongue, the sides of the pharynx, and the upper part of the larynx, and thus aid in the necessary movements of the vocal tract.

The nasal passage, divided into two ducts by a vertical partition, the vomer septum, was referred to in the chapter on inspiration. The so-called sinuses are hollow spaces in small bones on either side and above the nasal passage and communicating directly or indirectly with it. A question regarding the nasal cavity, including the sinuses, suggests itself. Of what use is the nasal passage as a cavity of resonance if, in order to prevent a nasal quality of tone, the passage during voice-emission is shut off by the action of the soft palate, or by the combined action of the soft palate, uvula and tongue? The answer is, first, that it is not always to be closed off, because there are times when a slightly nasal timbre in voice is desirable; secondly, that even when the nasal cavity is shut off, the hard palate being not only the roof of the mouth but also the floor of the nose, its vibrations are communicated to the nasal cavity, but not directly enough to give a disagreeable nasal quality to the voice.

From this survey it will be seen that the cavities of resonance along the vocal tract may be divided into such parts as are solid, pliable and movable. The solid parts are sharply resonant; they are, par excellence, the resonators in voice-production; while a pliable part, like the pharynx, although resonant in a less degree, is valuable in adjusting structural shape to every condition that arises; and the most movable parts of all, the tongue and the lips, probably wholly devoid of resonance, have their great rÔles to play in effecting what may be called wholesale changes in the size and shape of the mouth-cavity, which could not be brought about by any other agencies less mobile. The roof of the mouth, the teeth, the hard gums, the cones of the nasal passage, and the sinuses are the solid portions of the cavities of resonance. When Svengali gazed into Trilby's mouth and exclaimed, "Himmel, what a roof!" he spoke from the depths of vocal knowledge. For a highly arched mouth roof, especially if the tone enters the mouth cavity from a wide, well-rounded pharynx, is of great value to the singer. So is a fine, shapely, regular set of teeth, especially as regards the upper front teeth, behind which the vibrations appear to centre in so called "forward production." Cautiously brought into play, the posterior nasal passage assists, with its resonance, the head tones of the female voice and the upper range of male voices; but care must be taken not to carry the tone up into the nose and thus give it a nasal quality.

Some writers class the walls of the pharynx with the solid parts of the vocal tract. But the walls of the pharynx are pliable, as already has been pointed out, together with the admirable results to be derived from their flexibility when under the singer's control. The movable parts of or pertaining to the resonance-cavities are the soft palate with the uvula, the fauces, the cheeks, the lips, the lower jaw and, most mobile of all, the tongue.

The uvula often is too long, either by nature or through a disease called prolongation of the uvula. It can be treated by astringents or the elongation can be cut off, which usually is the most prompt and efficacious way. The operator, however, in case the patient is a singer, must calculate to a nicety just how much to remove, otherwise the voice will suffer. There are isolated cases of deformed soft palate with uvula so enormous that it cannot be raised. In such cases, one of which is instanced by Kofler, a surgical operation being out of the question, the patient simply has to give up singing.

Enlarged tonsils, whether from inflammation or other causes, also have to be operated on, as their enlargement obviously hinders free voice-emission. Even at its best the mouth-passage here is narrowest—and called the "isthmus"—and nothing must be allowed to make it narrower than it is by nature. The lips never should lie flat against the teeth, since this would muffle resonance. On the other hand, the teeth should not be bared, as this results in a foolish grin. The cheeks naturally conform to the action of the lips. The lower jaw should be relaxed, which gives the so-called "floating chin." When the lower jaw, and with it the chin, is raised, the throat is tightened, and voice-action becomes constricted. The "floating chin" does not, of course, mean that the chin is to be thrust downward into the chest. In singing, as in everything else, there is a golden rule to be observed.

It is obvious that the tongue also is a highly responsible member of the vocal tract. Raise it too high, and you bring it so close to the hard palate that the mouth becomes too small for free, resonant voice-emission. The tone becomes wheezy. Let the tongue lie too flat, and the mouth-cavity becomes too large and cavernous for tense, vibrant voice-emission. The tone becomes too open. Let the base of the tongue move back too far, and it will tend to close the pharynx and to check free egress from the pharynx into the mouth, making the tone muffled. Raise the back of the tongue until it touches the soft palate, and the two combined close the mouth-cavity from behind, with the result that voice is carried up the nasal passage and is charged with a disagreeable nasal quality.

For every tone produced there is a special adjustment throughout the entire vocal tract. These adjustments should, by practice, become automatic, simple acts of swift and unconscious obedience to the will. Then the question of "forward," "backward," or "middle" production, according to the part of the roof of the mouth where the tone-vibrations appear to centre, will become a matter wholly of the quality of voice which it is desired to produce for any given emotional state. Forward production—vibration appearing to centre a little back of the upper front teeth—is, as a general thing, the best. Yet a voice brilliant to the point of hardness can be mellowed by middle or backward production. These are matters of judgment. But when I am told, as I was by a young girl, that she was being taught to centre the tone-vibrations "back of her eyes," all I can do is to throw up my hands and exclaim, "O voice-production, what crimes are committed in thy name!" Yes—there should be a Rescue League, or a Society for the Prevention of Cruelty to Singers.