Frank E. Miller

THE PHYSIOLOGY AND PSYCHOLOGY OF VOICE-PRODUCTION

Above this chapter I might well have placed the following lines which George Eliot wrote above Chapter XXXI. of "Middlemarch."

The lines telling of the great bell stirred by the note of a flute played at the proper pitch suggest the moving power that lies in sympathetic vibration. The first time a military body crossed the Brooklyn Bridge, the spectators were surprised to hear the order given for the soldiers to march out of step. They had expected to be thrilled by the sight of a thousand men crossing the great structure in measured tread, with band playing and colors flying. They did not know that the structure, being a suspension bridge, might have been weakened and possibly destroyed by the force of rhythmic oscillation. Yet the accumulated force in the tramp of a thousand men is no greater than that which lies in the sympathetic vibrations of a musical note. Every metal structure has its note, and it is an old engineering saw that a huge structure like the Brooklyn Bridge eventually could be destroyed by the cumulative force of sympathetic vibration evoked by a musical instrument constantly reiterating the note of the bridge.

Sound has three dimensions: pitch, loudness and timbre.

Pitch depends upon the frequency of vibrations. The more rapid the vibrations, the higher the pitch.

Loudness is determined by the amplitude of the vibrations. As their length or "excursion" increases, so does the sound gain in loudness. Conversely, the diminution in the size of vibrations causes corresponding decrease of loudness.

Differences in the shapes of vibrations cause differences in quality or timbre.

After voice has originated within the restricted limits of the larynx, its power, its carrying quality is much augmented by the sympathetic vibrations within the resonance cavities above the larynx. These include the pharynx, nasal passages, mouth, bone cavities of the face—in fact pretty much every hollow space in the head, every space that will resound in response to vibration and assist in multiplying it. Moreover, the cavities of resonance by their differences in shape in different individuals determine the timbre or quality of individual voices. The chest, although situated below the larynx, is a resonance cavity of voice. In fact, in a certain register its vibration is felt so distinctly that we speak of these notes as being sung in the "chest register," which, so far as it implies that the tones are produced in the chest, is a misnomer. The same is true of "head register," in which vibration is felt in the head where, however, it is needless to say, the "head tones" do not originate.

Expiration—breath-emission—is the motor function of the vocal organs; and there are two other physical functions of the organs—vibratory and resonant.

Added to these is the sensory function, to which I attach great importance; and I call it a psychological function because it acts through the nerves upon the physical organs of voice. Without it the three physical functions—motor, vibratory and resonant combined—would remain ineffectual. They could generate voice, but it would be voice lacking those higher qualities that are summed up in the word "artistic." It would be a physical, not an art product, a product generated by the body without the coÖperation of the mind or soul. When it is considered that the larynx, in which the vocal cords are situated, is permeated by a network of muscles through which it is capable of some 16,000 adjustments and readjustments of shape, all of them pertinent to voice-production, and that the same thing also is true of the pliable portions of the resonance cavities; that these muscles act in response to an even finer network of nervous filament; and that the constant shaping and reshaping of various parts of the vocal tract during voice-emission is directed by messages from the mind, soul, or art-sense of the singer, messages which travel via nerve to muscle—the only route by which they can travel—it becomes possible to appreciate the importance of the sensory or psychological function which, I hold, should be added to the purely physical ones of motor, vibration and resonance. For by it these functions are enlisted in the service of art and made immediately and exquisitely responsive to the emotional exaltation of music and song. Nor are these vague terms. Psychology of song and psychological action in general may seem indefinite and unintelligible. They become, however, absolutely definite and intelligible when the part played by the nerves as intermediaries between mind and muscular action of a subtle and highly refined order is appreciated. The mind presses the button, the nerves carry the messages, and muscle acts instantaneously and responsively.

The student need not despair because so many separate acts seem necessary to the production of even a single tone. It is true that air has to be taken into the lungs and emitted from them; that it must be controlled by the singer as it passes up the windpipe; that the vocal cords and other parts of the larynx must be given their specific adjustment for each note; and the cavities of resonance shaped in sympathetic coÖrdination with those numerous adjustments, while the lips also have their function to perform. But it is equally true that correct instruction supplemented by assiduous practice merges all these separate acts into one. The singer thinks the note, forms what may be called a sounding vision of it in his mind, and straightway the vocal tract adapts and coÖrdinates all its parts to the artistic emission of that note. It is auto-suggestion become habit through practice.

Because the larynx is so important a factor in generating voice, writers on voice-production have described it with much minuteness, and because of these minute descriptions readers may have obtained an exaggerated idea of the size of this organ. But one of the marvels of voice-production is the smallness of the organ in which voice is generated, the size of the average larynx being about two inches in height by an inch and a half in width. Yet so numerous are the adjustments in shape of which this small organ is capable that the phenomenal soprano, Mara, could make 100 changes in pitch between any two notes in her voice, and as this had a compass of twenty-one notes, it follows that she could produce no less than 21,000 changes in pitch within a range of twenty-one notes. While in Mara's day this no doubt was attributed to a natural gift of voice, modern study of voice-physiology and of the metaphysics of voice-production readily accounts for it. It needs an ear naturally or by training so delicately attuned to pitch that not only all the fundamental notes of a voice, but all the numerous overtones at infinitesimal intervals are heard in what may be called the singer's mental ear; that the nerves convey each of these sounding mental conceptions to the intricate system of muscles in the larynx and resonant cavities and that the right muscles immediately adjust the larynx and cavities of resonance to the shape they have to assume to sound the corresponding note. Every vocal tone is, in fact, a mental concept reproduced as voice by the physical organs of voice-production, so that every vocal tone is, in its origin, a mental phenomenon. That is why an inaccurate ear for pitch results in a vocalist singing off pitch. His mental conception of the note is wrong, the message conveyed from the mind over the nerves to the muscles of the vocal organs is wrong, consequently they shape themselves for a note that is wrong, and, when the note issues from between the singer's lips, it is wrong—wrong from start to finish, from mind to lips. Thus again is illustrated the intimate connection between psychology and physiology in voice-production, and the necessity of having every function concerned therein so thoroughly trained that every act from mental concept to sounding voice is correctly performed through a habit so thoroughly acquired that it has become second nature. In common parlance one might say to the student of song, "Get the correct voice-habit and keep it up," for that really is what it amounts to, only it is necessary that great stress should be laid on the word "correct."

It now becomes necessary to describe the larynx, and this I will endeavor to accomplish without puzzling the reader with too many technical terms. The study of the larynx was made possible by the invention of the laryngoscope in 1855 by Manuel Garcia, a celebrated singing-master. It is a simple apparatus—which, however, does not detract from but rather adds to its value as an invention—and has been a boon to the physician in locating and curing affections of the throat. Its essentials are a small mirror fixed at an obtuse angle to a slender handle. Introduced into the mouth it can be placed in such position that the larynx is reflected in the mirror and thus can be observed by the operator. Those who have had their throats examined with the laryngoscope will recall that the operator wears a reflector over his right eye. Through a central perforation in the reflector he views the image, which is seen the more clearly for the light thrown upon the laryngoscopal mirror by the reflector. It would be possible after comparatively little practice with the apparatus for a singer to examine his own larynx. But it would be most inadvisable for him to do so. Either he soon would become "hipped" on the subject of innumerable imaginary throat troubles, or his voice-production would become mechanical, which is very different from the spontaneous adjustment of the vocal tract described above.

The laryngoscope should not, in fact, leave the hands of the physician. Invaluable for the detection of diseases of the throat which impair the voice and which have to be cured either by treatment or operation before the voice can be restored to its original potency or charm, its value in studying the physiology of voice-production and the functions of the vocal organs is doubtful. In fact, it is its use by amateur laryngoscopists that has resulted in the promulgation of all kinds of absurd theories of voice-study and in those innumerable pet methods of vocal instruction, each one of which may safely be guaranteed to destroy expeditiously whatever of voice originally existed. Fascinating as it may seem to the singer to examine his own larynx while he is producing a vocal tone—"during phonation," the physiologist would say—the value of the deductions formed from such observation may be doubted, if for no other reason than that the introduction of the mirror into the back of the mouth makes the whole act of phonation strained and the effects observed unnatural. In fact, as Mackenzie already has pointed out, although the laryngoscope is invaluable in the recognition and treatment of diseases which before only could be guessed at, "with the exception of certain points relating to the 'falsetto' register, it can scarcely be said to have thrown any new light on the mechanism of the voice." In other words, the instrument belongs in the hands of the physician, not in those of the singer.

The larynx, as I already have stated, is a small organ, on an average two inches long and one and a half inch wide. The reader can form a good idea of its location by the Adam's apple, which is its most forward projection at the top.

From the singer's point of view the larynx exists for the sake of the vocal cords—in order that they may be acted upon by certain muscles and thus relaxed or tightened, lengthened or shortened, or by a combination of these states properly adjusted to the note that is to be produced. The vocal cords lie parallel to each other. The space between them (the opening through which the air from the windpipe passes up into the larynx) is called the glottis. With every loosening, tightening, lengthening or shortening of the vocal cords or other effect of muscular action upon them, the space between them—the glottis—alters in size and shape. These subtle changes in the size and shape of the glottis are, as I shall expect to show, of great importance in voice-production. They form the first step in the actual creation of voice.

The numerous and subtle adjustments and readjustments in shape of which the larynx is capable could not be effected if its shell consisted of so hard and unyielding a substance as bone. Consequently, it has to consist of a substance which, while sufficiently solid to form a background for the attachment of its numerous muscles, yet is sufficiently pliable to yield with a certain degree of elasticity to the action of these. Nature therefore has built up the larynx with cartilage, or gristle, providing a framework made up of a series of cartilages, sufficiently joined to form a firm shell surrounding the muscular tissue, yet, being hinged as well as joined, capable of independent as well as of combined movement, and, withal, possessing the requisite degree of pliability to respond in whole or part to the extremely varied and often delicate action of the laryngeal muscles—muscles which indeed are required to be as practised and as sensitive to suggestion as if they were nerves.

The principal cartilage of the larynx is the thyroid or shield cartilage, named from the Greek thureos (shield). It really consists of two shields joined along the edges in front (its most forward upper projection being the Adam's apple) and opening out at the back. The thyroid is the uppermost cartilage of the larynx and the Adam's apple is the uppermost portion of the front of the larynx. But as the shields open out back of the Adam's apple, they slope upward and at the extreme back each shield has a marked upward prolongation like a horn. By these horns, enforced by membrane, the thyroid cartilage and through it the whole larynx is attached to and is suspended from the hyoid bone, or tongue-bone. This gives mobility to the larynx and freedom of movement to the neck; and the larynx, while mobile as a whole, furthermore is capable of an infinite number of muscular adjustments and readjustments within itself.

At the back the lower edges of the thyroid rest upon the cricoid cartilage, which derives its name from the Greek krikos, a signet-ring. This is next in size to the thyroid. The broader portion, the part which corresponds to the seal in a signet-ring, is at the back. Attached at the back, the two cartilages do not, however, meet in front. Place a finger on the Adam's apple, slide it down a little way, and the slight depression there met with locates the front opening, covered with yielding membrane, between the thyroid and cricoid cartilages.

On the broader part of the cricoid—that is, on the part in the back of the larynx—and rising inside the thyroid are two smaller cartilages, the arytenoid or ladle cartilages, named from the Greek arutaina, a ladle. Though smaller than either thyroid or cricoid, they are highly important, because they form points of attachment for the vocal cords. These (the vocal cords) are attached in front to the inner part of the angle formed by the two wings of the thyroid just back of the Adam's apple, and behind to a forward projecting spur at the base of each of the arytenoid cartilages, which for this reason often are spoken of as the "vocal process."

The vocal cords, as has been stated, lie parallel to each other, and the space between them is known as the glottis or chink of the glottis. Above the glottis and on opposite sides are two pockets or ventricles, and above these are the so-called false cords or ventricular bands. The pockets are, in fact, bordered below by the vocal cords and above by the false cords. The false cords or ventricular bands (a name given to them by Mackenzie) are the lower edges of membranous folds that form the upper entrance to the larynx. Here are two pairs of small cartilages, the cartilages of Santorini and the cartilages of Wrisberg. Usually they are dismissed as of little or no importance. Yet they have, in connection with muscles located in that part of the larynx, their rÔles to play in those numerous adjustments and readjustments which, as I shall show a little later on, are of the greatest importance in voice-generation. For I consider, as I also will show, that the numerous, indeed innumerable, and extremely subtle and exquisite changes of shape of which the larynx is capable within itself, have much to do with the actual creation of the tone which eventually issues from the lips; although I believe this statement to be contrary to all accepted authority. For the present, however, I must content myself with this mere statement.

The larynx is protected above by a lid, a flexible, leaf-shaped cartilage, the epiglottis. The gullet, or food-passage to the stomach, is situated behind the larynx and windpipe, and the function of the epiglottis is to close the larynx and to act as a bridge over which food passes from the mouth into the gullet. But for the epiglottis, food might get into the larynx and thence into the windpipe every time we swallowed, with what distressing and even disastrous effect any one who has ever "swallowed the wrong way" well knows. When open, on the other hand, the epiglottis forms a beautifully smooth cartilaginous curve, over which the sounding air, the tone, as it issues from the larynx, is guided to the resonance cavities above the larynx, which are the cavities of the mouth and of the nose. While parts of these cavities are solid, like the roof of the mouth, other parts, like the soft palate, are pliable; while the tongue is so astoundingly mobile that it constantly can alter the resonance cavity of the mouth as to dimension and shape.

The larynx is swathed and lined with membrane and muscle. These membranes and muscles are named after the cartilages to which they are attached, between which they lie, or which they operate. There is no reason why they should be enumerated now. The function of the muscles of the larynx is stated by all authorities with which I am familiar to be twofold—to open and close the glottis (the space between the vocal cords), and to regulate the tension of the vocal cords, because the vibrations of these are considered the determining factor of vocal pitch. Sir Morell Mackenzie, however, in describing the muscles of the larynx in a passage couched in untechnical language, unconsciously gives a hint of another purpose for which the complexity of muscles in the larynx may exist. After speaking of the "innumerable little fingers of the muscles which move the vocal cords," he continues: "These fingers (which prosaic anatomists call fibres), besides being almost countless in number, are arranged in so intricate a manner that every one who dissects them finds out something new, which, it is needless to say, is forthwith given to the world as an important discovery. It is probable that no amount of macerating or teasing ever will bring us to 'finality' in this matter; nor do I think it would profit us much as regards our knowledge of the physiology of the voice if the last fibrilla of tiny muscle were run to earth. The mind can form no clearer notions of the infinitely little than of the infinitely great, and the microscopic movements of these tiny strips of contractile tissue would be no more real to us than the figures which express the rapidity of light and the vast stretches of astronomical time and distance. Moreover, no two persons have their laryngeal muscles arranged in precisely the same manner—a circumstance which of itself goes a considerable way toward explaining the almost infinite variety of human voices. The wonderful diversity of expression in faces which structurally, as we may say, are almost identical, is due to minute differences in the arrangement of the little muscles which move the skin. The same thing holds good of the larynx."

These are significant words. The distinguished physician who wrote them might just as well have said that the generally prevailing theory that in voice-production the muscles of the larynx exist solely to open and close the glottis and to regulate the tension and hence the vibration of the vocal cords, is incorrect. For they also exist in order to shape and reshape the entire larynx within itself according to the note to be produced, and the opening or closing of the glottis with the degree of tension of the vocal cords resulting therefrom is but one detail in the coÖrdination of adjustments and readjustments which prepare the vocal tract to produce the tone the singer hears in his mind. Nearly every authority on the physiology of voice-production believes that the vocal tone is produced solely by the vibration of the vocal cords, and that the entire vocal tract situated above the vocal cords is concerned merely with augmenting the tone and determining its timbre or quality. Let us examine this theory and ascertain how tenable it is.

To begin with, the term "cord" as applied to the vocal cords is misleading. It suggests a resemblance between the vocal cords and the strings of a violin, which are capable of great tension, or at least a resemblance between the vocal cords and the vibrating reed of a reed-instrument. In point of fact, the vocal cords are neither strings nor reeds, and are not even freely suspended from end to end or from one end like reeds, but are attached along their entire lower portion to the inner wall of the larynx. Therefore they are not cords, nor strings, nor reeds in any sense whatsoever. They are shelves composed of flesh and muscle, their substance resembles neither the catgut of which the strings of stringed instruments are made nor the cane, wood or metal of which the reeds of reed-instruments are formed; and the entire length of each cord is a trifle more than half an inch in men and a little less than half an inch in women. Almost every writer on voice appears to consider the term "cord" as applied to them a misnomer. They have been spoken of as membranous lips. "The vocal 'cord' is not a string, but the free edge of a projecting fold of membrane," says Mackenzie. Yet it is not only claimed but announced over and over again as a physiological fact that the human voice, sometimes sweet and mellow, sometimes tense and vibrant and with its great range, is produced solely by the vibration of two projecting folds of membrane, free only at their edges and at their longest only a little over half an inch in length.

At least one writer on voice-production, Prof. Wesley Mills, appears to have doubted the correctness of the old and oft-repeated theory. "Allusion must be made," he writes in "Voice-Production in Singing and Speaking," "to the danger of those engaged in mathematical and physical investigation applying their conclusions in too rigid a manner to the animal body. It was held until recently that the pitch of a vocal tone was determined solely by the number of vibrations of the vocal bands, as if they acted like the strings of a violin or the reed of a clarinet, while the resonance chambers were thought to simply take up these vibrations and determine nothing but the quality of tone.... It seems probable that the vocal bands so beat the air within the resonance chambers as to determine the rate of vibration of the air of these cavities, and so the pitch of the tone produced." This at least shows dissatisfaction with the old theory and attaches some share of their due importance to the resonance cavities, but it still is far from describing the correct phenomenon of voice-production.

Show a lateral section of a larynx to a trumpet or horn player and he will at once recognize its similarity to the cupped mouthpiece and tube of trumpet or horn, the cup in the larynx being formed by the ventricles or pockets above the vocal cords. Extend the picture so that it includes not only the larynx but the resonance cavities of the head as well, and the cornet, trumpet or horn player will recognize the similarity to the tube of his instrument as it turns upon itself. The manner in which the lips shape themselves as the player blows into the instrument, the form and size of the cup, the gyration and friction of the air within it and within the bent portion of the tube, determine the pitch and the quality of the tone that issues from the bell of the instrument.

The shape assumed by the lips, which are capable of many exquisite variations in shape, conditions the form of the air-column as it enters the cup of the trumpet or horn. This I believe to be one important function performed for the larynx by the vocal cords, which Mackenzie, with an aptness he could not have appreciated, called the lips of the glottis. They are, in fact, the lips of the essential organ of voice, the larynx. If they are looked at from below they will be seen to be bevelled, and their resemblance to lips even more striking.

While, however, the importance of the vocal cords in tone-production has been overestimated, I should be going to the opposite extreme if I limited their importance to their function as the lips of the glottis. Not only are they lips, but vibrating lips, their vibrations, however, requiring enforcement through the sympathetic vibrations which they generate within the cup of the larynx and in the cavities above. As lips, the vocal cords shape the air-column as it enters the larynx, to the required note; as vibrating lips—set into vibration by the very air-column to which they have given shape—they start the vibrations essential to pitch and pass them along into the cup of the larynx, which also has shaped itself to the note and where gyration and friction begin to reinforce the vibrations started by the cords. What is true of the cup also is true of the resonance-cavities. In other words, the entire vocal tract, from cords to lips, shapes and reshapes itself with reference to the tone that is to be produced, and what thus goes on above the vibrating cords coÖperates to produce the effect formerly attributed to the cords alone.

The fact that the cup of the larynx subtly changes its shape for each tone produced, makes the hitherto obscure subject of registers of the voice, which many writers have written around but none about, perfectly clear. The cup assumes what may be called a generic shape for each register, and then goes through subtle adjustments of shape for the different notes within each register. But this is a subject to be taken up in detail later.

The reader now will understand why at different points in this chapter I have emphasized the fact that the larynx as a whole and throughout all its parts is capable of numerous adjustments in shape, and that the same is true of the resonance-cavities. The vocal tract of an accomplished singer is capable of as many adjustments as a sensitive face is of changes in expression. This phenomenon is the vocal tract making ready to generate, vitalize and emit the tone suggested by the mind—mind pressing the button, the physical organs of voice-production doing the rest.