Physiology Of The Voice

In former times the culture of the singing-voice was conducted upon

purely empirical grounds. Teachers followed a few good rules which had

been logically evolved from the experience of many schools of singing.

We are indebted to modern science, aided by the laryngoscope, for many

facts concerning the action of the larynx, and more especially the vocal

cords in tone-production. While the early discoveries regarding the
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mechanism of the voice were hopefully believed to have solved all

problems concerning its cultivation, experience has shown the futility

of attempting to formulate a set of rules for voice-culture based alone

upon the incomplete data furnished by the laryngoscope. This instrument

is a small, round mirror which is introduced into the throat at such an

angle, that if horizontal rays of light are thrown upon it, the larynx,

which lies directly beneath, is illuminated and reflected in the mirror

at the back of the mouth-- the laryngoscope. Very many singers and

teachers, of whom Manuel Garcia was the first, have made use of this

instrument to observe the action of their vocal bands in the act of

singing, and the results of these observations are of the greatest

value. Still, as before said, the laryngoscope does not reveal all the

secrets of voice-production. While it tells unerringly of any departure

from the normal, or of pathological change in the larynx, it does not

tell whether the larynx belongs to the greatest living singer or to one

absolutely unendowed with the power of song. Also, the subject of vocal

registers is as vexing to-day as ever.

While, then, we may confidently expect further and more complete

elucidation of the physiology of the voice, there is yet sufficient data

to guide us safely in vocal training, if we neglect not the empirical

rules which the accumulated experience of the past has established.

The organ by which the singing-voice is produced is the larynx. It forms

the upper extremity of the windpipe, which again is the upper portion

and beginning of the bronchial tubes, which, extending downward, branch

off from its lower part to either side of the chest and continually

subdivide until they become like little twigs, around which cluster the

constituent parts of the lungs, which form the bellows for the supply of

air necessary to the performance of vocal functions. Above, the larynx

opens into the throat and the cavities of the pharynx, mouth, nose, and

its accessory cavities, which constitute the resonator for vocal

vibrations set up within the larynx.

The larynx itself consists of a framework of cartilages joined by

elastic membranes or ligaments, and joints. These cartilages move freely

toward and upon each other by means of attached muscles. Also the larynx

as a whole can be moved in various directions by means of extrinsic

muscles joined to points above and below.

The vocal bands are two ligaments or folds of mucous membrane attached

in front to the largest cartilage of the larynx, called the thyroid, and

which forms in man the protuberance commonly called Adam's apple; and,

extending horizontally backward, are inserted posteriorly into the

arytenoid cartilages, the right vocal band into the right arytenoid

cartilage and the left band into the left cartilage. These arytenoid

cartilages, by means of an articulation or joint, move freely upon the

cricoid, the second large cartilage of the larynx, forming its base, and

sometimes called the ring cartilage, from its resemblance in shape to a

seal ring. The vocal bands are composed of numberless elastic fibres

running in part parallel to each other, and in part interwoven in

various directions with each other. The fibres also vary in length; some

are inserted into the extending projections, called processes of the

arytenoid cartilages, and some extend further back and are inserted into

the body of the cartilages. The vocal bands, then, lie opposite each

other, on a level, raised a little in front, and with a narrow slit

between, called the glottis.

The muscles controlling the action of the vocal bands, and which

regulate the mechanism producing sound, are of three groups, viz.,

abductors (drawing-apart muscles), adductors (drawing-together muscles),

and tensors.

The abductors act to keep the bands apart during respiration, while the

function of the adductors and tensors is to bring the bands into

position for speech or singing. They are, since phonation is at will,

voluntary muscles; but it is an interesting fact that the laryngeal

muscles of either side invariably act together. It has been shown that

it is not possible to move one vocal cord without the other at the same

time executing the same movement. It is thus shown that the laryngeal

muscles are, to a less extent, under the control of the will than are

those of either hand or eye. The rational training of the singing-voice

cannot, therefore, proceed upon any theory based upon the voluntary

training of the muscles controlling the movements of the vocal cords.

The mucous membrane which lines the larynx is liberally supplied with

secreting glands, whose function is to keep the parts moist. Above the

vocal bands, another pair of membranous ligaments are stretched across

the larynx forming, with its sides and the vocal bands, a pouch or

pocket. The upper ligaments are sometimes called the false vocal cords,

but are more properly termed ventricular bands. Their function has

occasioned much speculation, but whatever modification of tone they may

be supposed to produce, they no doubt protect the true vocal bands and

permit their free vibration. The larynx, in the production of sound, may

be compared to an organ-pipe. The two vocal cords which act

simultaneously and are anatomically alike, when set in vibration by the

blast of air coming from the lungs, correspond to the reed of the

organ-pipe; the vibration of the cords, producing sound, which is

communicated to the air enclosed in the cavities of the chest and head.

Pitch of tone is determined by the rapidity of vibrations of the bands,

according to acoustical law, and the length, size, and tension of the

cords will determine the number of vibrations per second, i.e., their


Strength or loudness of tone is determined primarily by the width or

amplitude of the vibrations of the vocal membrane, and quality or timbre

is determined by the form of the vibration.

The infinitely varying anatomical divergencies in the form and structure

of the nasal, pharyngeal and throat cavities, and possibly the

composition of the vocal bands, modifies, in numberless ways, the

character of tone in speech or song. It is a fascinating topic, but must

be dismissed here with the remark that, as those anatomical differences

in structure are far less marked in children than in adults, their

voices are, in consequence, more alike in quality and strength. It takes

long, patient training to blend adult voices, but children's voices,

when properly used, are homogeneous in tone.

The voices of boys and girls, prior to the age of puberty, are alike.

The growth of the larynx, which in each is quite rapid up to the age of

six years, then, according to all authorities with which the writer is

conversant, ceases, and the vocal bands neither lengthen nor thicken, to

any appreciable extent, before the time of change of voice, which occurs

at the age of puberty.

It is scarcely possible, however, that the larynx literally remains

unchanged through the period of the child's life, extending from the

age of six to fourteen or fifteen years. In point of fact, authorities

upon the subject refer only to the lack of growth and development in

size of the larynx during the period; but undoubtedly, during these

years, there is a constant gaining of firmness and strength, in both the

cartilages and their connecting membranes and muscles. None of the

books written upon the voice have even mentioned this most important

fact. It bears with great significance upon questions relating to the

capacities of the child's voice at different ages, and explains that

phenomenon called the "movable break," which has puzzled so many in

their investigations of the registers of the child's voice. The

constant, though of course extremely slow, hardening of the

cartilaginous portions of the larynx, and the steady increase in the

strength of its muscles and ligaments is not in the least inconsistent

with the previously noted fact, that the vocal bands during this time

increase to no appreciable extent in length; for, it may be observed,

after the change of voice, which often occurs with great rapidity, and

during which the vocal bands increase to double their previous length in

males, that, though the pitch of the voice, owing to increased length of

the bands, suddenly lowers, yet not until full maturity is reached, do

the laryngeal cartilages attain that rigidity, or the vocal bands that

ready elasticity essential to the production of pure, resonant voice.

Yet, during these years, while the voice is developing, the vocal bands

remain unchanged in length. Even in those cases where the voice

changes slowly in consequence of the slow growth in length and thickness

of the vocal cords, it takes several years, after laryngeal development

has ceased, for the voice to attain its full size and resonance.

Furthermore, the continual increase in strength and firmness of the

larynx from six years onward to puberty, is consistent with the constant

growth in strength and firmness of tissue characterizing the entire

body. It is again proven by the continual improvement in the power and

timbre of the tone through this period, always premising, be it

understood, that the voice is used properly, and never forced beyond its

natural capabilities. The voice, at the age of eleven or twelve, is far

stronger, and is capable of more sustained effort than at the age of six

or seven years, and, for the year or two preceding the break of voice,

the brilliance and power of boys' voices, especially in the higher

tones, is often phenomenal, and in all cases is far superior to that of

previous years.

The resemblance between the voices of boys and girls, a resemblance

which amounts to identity, save that the voices of boys are stronger and

more brilliant in quality, disappears at puberty.

Among the physical changes which occur at this period is a marked growth

of the larynx, sufficient to alter entirely the pitch and character of

the boy's voice. As a female larynx is affected to a lesser extent, the

voices of girls undergo little change in pitch, but become eventually

more powerful, and richer in tone.

This break of the voice, as it is called, occurs at about the age of

fifteen years in this climate, but often a year or two earlier, and not

infrequently a year or two later. The growth of the larynx goes on, with

greater or less rapidity, varying in different individuals, for from six

months to two or three years, until it attains its final size. In boys,

the larynx doubles in size, and the vocal bands increase in the

proportion of five to ten in length. This great gain in the length of

the vocal cords is due to the lateral development of the larynx, for the

male larynx, in its entirety, increases more in depth than in height.

The result is a drop of an octave in the average boy's voice, the longer

bands producing lower tones. The change in size in the female larynx is

in the proportion of five to seven, and the increase is in height

instead of depth or width as in the male larynx. The vocal cords of

women are, therefore, shorter, thinner and narrower than are those of


The reason assigned for the peculiar antics of the boy's voice, during

the break, is unequal rapidity in the growth and development of the

cartilages and of the muscles of the larynx. The muscles develop more

slowly than do the cartilages, and so abnormal physical conditions

produce abnormal results in phonation.

No further changes occur in the laryngeal structure until middle life,

when ossification of the cartilages commences. The thyroid is first

affected, then the cricoid, and the arytenoids much later.

The consequent rigidity of the larynx occasions diminished compass of

the singing-voice, the notes of the upper register being the first to

disappear. In some few cases of arrested development, the voice of the

man retains the soprano compass of the boy through life.