Hygiene of the voice. Its physiology and anatomy

Front matter

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OF

PHE VOICE

Chapter I. Sound

PITCH INTENSITY QUALITY.

The natural phenomena which are incessantly developing themselves on our earth and in the vast space around us, offer to our view so magnificent a spectacle, that the curiosity of the most listless observer becomes powerfully aroused, and in spite of himself he is compelled, in a greater or less degree, to meditate upon the causes capable of producing such marvellous effects.

Ever since scientific men began to attempt the explanation of these natural phenomena, they have observed and collected a great number of facts, quite distinct from each other, which they have classified under such different heads as Light, Heat, Electricity, Sound, etc. We can easily distinguish these phenomena from each other, but when we attempt their explanation, to discover the causes 1* which produce them, we are as much in the dark as we are in regard to the soul, or the vital principle.

The human mind, always prone to generalize and to consider unity of means as perfection, went so far as to assign to heat, light, electricity, and sound — and with great probability of correctness — a common principle : vibratory movements or waves acting upon different organs ; and asserted that the different sensations arose from peculiar conditions of relative motion among the elements of which our physical organizations are composed, the conditions of motion being determined by the internal state of the bodies with which we are in contact. May it not be true that the light which strikes the eye produces its impression upon the retina as heat, and that the sounds which strike the ear produce their imj^ression upon the nerves of hearing as motion ? It is the same cause which produces these effects, whether it is propagated through an imponderable fluid as the ether, or through the air, that is to say, by vibration.

Indeed, we may go farther still, and say that, since matter manifests itself to us by all these different phenomena, which are after all but vibratory movements of the molecules of the body, transmitted to us as waves, it results of necessity that vibratory motion is an inherent quality of bodies.

For the mind which sees beyond external appearances, matter, from the very fact that we perceive it in some way, is always in motion. If a light is removed from onr eye, so that we see it no longer, shall we say that the vibrations of the ethereal medium have ceased ? If a sound descends from a tone excessively high to one so low that we are no longer able to bear it, are we justified in affirming that the sonorous body, or that the air, has ceased to vibrate \ Evidently not. Reason tells us, on the contrary, that the rest is relative only and not absolute, and that the body still vibrates, but that on account of the imperfection of our ear, we are only enabled to perceive those sounds whose vibrations have a certain intensity and rapidity, and that vibration may still exist in a sonorous body, although unable to produce an impression on the ear.

If, therefore, every thing is in motion, every thing vibrates, every thing resounds, there is only required a medium subtle enough to transmit, and an organ delicate enough to perceive, these vibrations in order that we might live in the midst of sounds, as we do in the midst of light.

Between light and sound, the analogy has often been made, and this in all ages has given birth to thousands of comparisons between musical tones and colors : between music and painting. That this analogy exists, is indisputable ; but we must be on our guard lest we carry it farther than the nature of the case will allow. It is true that it may serve as a source of metaphor, but we must not claim for it any scientific value whatever. If, since the varying rapidity of vibration produces the different colors as well as tones, in considering the resemblance between music and painting, we should find that the number of vibrations corresponding to the red of the chromatic scale bear the same relation to the number corresponding to C of the acoustic scale as that for the orange does to that for D, or that for the yellow does to that for E, or even that the proportion should hold good throughout both the chromatic and acoustic gamuts, nevertheless, we should not be justified in asserting, from this resemblance, that a complete identity had been established ; and imagine that a harpsichord of colors might be constructed on which we would be able to play tunes with the eyes.

When we hear a musical scale executed, we need but to listen to a few notes to perceive a difference in the pitch or note of the sounds.

This is not the only difference we notice : we know that two sounds alike as to their note may differ as to their volume, or the more or less decided impression they make upon the tympanum. We have, therefore, another characteristic difference besides the pitch — the intensity or loudness.

But is this all? Can we not distinguish the difference between the sound of a fresh, girlish voice, and the rough, worn-out voice of a street-singer ? Or, to use the words of Laugel, " I wish to know why the sighs of the hautboy differ from the twang of the violin, from the blare of the trumpet, from the subdued sounds of the horn, from the soft nasillements of the bassoon; to understand why the varied stops of the organ differ; why its harmonies float froni thunder-peals to sounds so sweet that they seem the flappings of seraphic wings ; why its breath now thrills me through, and now caresses me as with invisible kisses ? " There exists, then, a third character, or distinction of sounds, a character more definite, more decided than the other two, which may be called its physiognomy, its color, its perfume, and which the reader has already recognized as the timbre or quality. We have now all the characteristic differences between sounds ; two notes of the same. pitch, of the same intensity, and of the same timbre are completely identical.

PITCH.

The pitch, or note of a sound, whether it be acute or grave, depends upon the number of vibrations of the sonorous body in a given period of time, as, for example, during a second. The highest or most acute sound would be the one produced by the greatest number of vibrations of which the ear could take cognizance, and consequently of the most rapid motion of the auditory nerves possible, while, on the other hand, the lowest or gravest note would be produced by the least number of vibrations ca]3able of producing an effect upon the ear. But, as we have already said, the sensibility of the nervous apparatus is limited. The number of vibrations must be comprised between given limits, in order that the sound jxroduced shall be audible : should the number of vibrations be too great or too small, the resulting sounds would escape us. It has been found by exjDerinients that the deepest or gravest sound audible to the human ear must be produced by at least from 7 to 15 vibrations per second, and that the sound becomes distinctly audible only when the number becomes some 64. On the other hand, the greatest number of vibrations producing the highest or most acute sound audible to our ear, cannot be greater than 30,000, and this number makes a very disagreeable impression upon the ear.*

* According to Weber, musicians who possess an extremely accurate and well-trained ear, are able to perceive a difference of pitch when the ratio of the vibrations is 1,000 to 1,001. The difference would be about - 6 ^f of a semitone.

We will not speak of sounds produced by some 65,000 vibrations in a second, for besides the difficulty of obtaining them, they are imperceptible to almost all human ears, though they are distinctly perceptible to certain animals, differently organized from us, cats for example.

But this is not all. Besides these sounds which escape the ear on account of the small or of the great number of the vibrations by which they are produced, that is to say, those which are too grave or too acute, we observe also that this same imperfection of the organ of hearing does not allow it to distinguish between two sounds which differ only by a small number of vibrations — although in reality one may be more acute than the other — so, if a cord is set vibrating, and then, by the application of a continued and gradually increasing force, the tension of the cord is augmented, the cord vibrates more and more rapidly, and the pitch of the sounds is increased, but by degrees which are inappreciable to the human ear, as may be easily demonstrated by experiment. But between the starting-point, which we will suppose to have been a cord stretched by its own weight, and the extreme point of tension, where the cohesive force of the particles of which the cord is composed, is just sufficient to overcome the efforts of the tensile force to produce rupture, many sounds differing in pitch have been produced, and while the ear has not been able to distinguish one from the other, so insensible has the gradation been; just as in the spectrum of the prism the eye is not able to distinguish the precise point where one color begins and another ends, It has been found necessary, therefore, to establish a line of decided demarcation between sounds, neglecting those which serve as transitions, and keeping those only which, possessing the most definite qualities, produce, consequently, the most distinct and agreeable impressions.

The arbitrary scale, or series of notes produced in this way, is called the gamut. The gamut is, then, nothing but a choice of certain intervals, and the particular name given to each step of the ladder indicates the moment at which a sound differs sensibly from another.

If the sounds of the gamut be made to succeed each other, it will be found that they do not all produce the same sensation of pleasure ; some fully satisfy the ear, by imparting to the sensibility an idea of fulness and completeness ; others excite, disturb, or cause a desire for a more clear, more easy transition, and require, in order that an agreeable impression may be produced, to be completed by one of the former. It is in that happy combination of different intervals, that the charm of melody exists.

INTENSITY.

The intensity of sound results from the amj)litude of the vibrations, — in other words, the intensity is the quantity of strength with which the body is set in motion ; and, in order that intensity may be appreciated by the ear, it is necessary that the vibrations should be transmitted in their varying amplitude to the tympanum, so that we might define intensity to be the varying degree of motion imparted by the vibrations to the nervous fasciculi. A very weak or grave sound is powerless to stretch the tympanum, or to agitate the nerves of the ear ; while a very violent sound — that caused by the discharge of a cannon, for example — may rupture the tympanum, or produce grave disorders in the nervous mechanism of the ear. But between these two extremes there is room for a great variety of agreeable sounds, which music can vary ad infinitum, and by means of which it is enabled to produce its almost unlimited power over its listeners. What is termed expression, if we except a few means borrowed from the timbre, consists almost exclusively of the shades of intensity.

TIMBRE. (Quality.)

Until now, we have examined only the strength and the rapidity of the vibrations, but we have yet to consider their form, and reason tells us that here we shall find the explanation of the timbre or quality.

The different molecules of which bodies are composed, are not all disposed in the same way : when a vibratory motion is induced on the body, all the molecules of which it is composed describe orbits around their centre of rest, but their orbits of motion are differently disposed in reference to the direction in which the sound is propagated to reach the ear; some orbits having the plane of motion in the direction of sound propagation, some at various angles ; and these various motions are transmitted to the air and thus to the ear.

And still further, in consequence of that varied disposition of the molecules of a body which permits some of them to vibrate strongly, some feebly, whilst others remain almost absolutely at rest, it follows that a sound is always, or at least very often, mixed with accessory sounds which disappear in the principal sound. If the string of a violin is forcibly pinched, or set in motion by a bow, a delicate ear will detect at the same time, and like a slight emanation of the fundamental note, the third, the fifth, the octave, etc.

Habit enables us to isolate these sounds from one another. They are the elements out of which the science of harmonics is made up.

A sound, then, taken as a whole, is complex, just as white light is, and just as the prism can separate sunlight into the primary colors, so a nice ear can distinguish, at the same time with the primary, the secondary sounds. Hence we have in the ear" an infinite number of nervous cords, some of which are acted upon violently by the principal vibrations and give the chief impression of tone, whilst others, agitated more feebly by the secondary sounds, serve only to modify the principal impression ; and it is for this reason that any person, although he may not have a very delicate ear, easily recognizes the timbre.

We may, then, define the timbre to be the result of accessory sounds, harmonic when the sound is musical, inharmonic when it is a noise, and say that it varies according to their number and pitch. Experiment has shown that, when the partial sounds change, the timbre also changes, and hence the explanation of the timbre : that as we modify either the molecular arrangement of the substance, or the substance itself which is vibrating, or the column of air which forms the conducting medium, we modify the orbital motion of the molecules, and therefore the accessory sounds ; for the timbre is nothing less than the form of the vibration of the air, reproducing itself exactly on the nervous matter of the ear. (Beauquier.)

Chapter II. Historic Summary Of The Theories Of The For- Mation Of The Voice

Though a great number of theories have been successively advanced to explain the voice, its formation, and the various ]3henomena which it presents, yet they may be all classed under three principal groups : 1st. Those in which the vocal organ is compared to a wind instrument with an inflexible mouthpiece, as the flute, flageolet, or the organ-pipes ; 2d. Those in which it is compared to a wind instrument having a reeded mouthpiece, as the clarionet, bassoon, etc. ; and 3d. Where it is supposed to resemble a string instrument, or one partaking both of the character of a string and wind instrument.

A brief summary of the opinions held by some of the most eminent physiologists, of both ancient and modern times, will show this statement to be correct.

Hippocrates, 400 B.C., says : " Man speaks by the air which he draws in the whole body but especially in the cavities. Pushed to the exterior

HISTOETC SUMMAEY. 21

by the vacuum, the air engenders a sound, the tongue articulates by its clashings, intercepting it in the throat, and striking against the palate and the teeth, it makes the sound distinct."

Ninety years later, Aristotle defines the voice to be "a certain sound produced by a living body, for inanimate things have no voice." He compares the organs of the voice to a flute ; the trachea being the body of the instrument.

Plato, 429 b. c, defines the voice to be " a rustling in the air reaching the soul through the ears."

Galen, 131 b. c, shows a far more intimate acquaintance with the structure of the vocal apparatus, for he states the thorax to be the bellows, or reservoir for air ; the vocal cords, the sonorous vibrating body, by which the sound is produced, and the palate and mouth to correspond to the tube of a wind instrument, by which the sounds are modified, — the whole apparatus being considered by him as analogous to a flute.

In the 16th century, Jerome Fabricio, speaking of the vocal apparatus, says : " The general efficient cause of sound is a body capable of condensing, compressing, striking the air, and making it break forth." His description would make the vocal organ similar to an organ-pipe.

Mersenne, 1588, says: "The faculty or motive power of the soul is the principal and first cause of the voice in animals and has its seat in the tendons." However, Mersenne did not say whether he considered the vocal instrument as wind or string.

Claude Perranlt, 17th century, says : u The voice is a sound of verberation, which the air enclosed in the chest excites in sallying forth violently, and in grazing the membranes constituting the glottis, so that it shakes its parts, and disseminates its particles, the return of which causes an agitation in the air, capable of making an impression on the organ of hearing." He also classes the vocal organ with instruments of the flute kind.

Dodart, 1700, says: "The voice is a sound — sound is an effect of the air beaten violently — the matter of the voice is the air contained in the lungs, pushed from downward upward, from inside outside. The resounding of any sound, and consequently that of the voice, supposes the voice already formed, and is only the continuation of the sound. The glottis alone," said he, "forms the voice and all its tones." He compares the organ of the voice to a horn or trumpet.

Ferrein, in 1742, was the first who attempted to draw sounds from the larynx of the dead. " I approximated," said he, " the lips of the glottis, and blew with force into the windpipe; upon this the organ seemed to take life, and sent forth, I will

HISTORIC SUMMARY. 23

not say a sound, but a loud voice, more agreeable to me than the most touching music." Ferrein considered the larynx as a stringed instrument, and compared it to a violin.

The great naturalist, Cuvier, compared the vocal organ to a flute, and looked upon the glottis as the mouthpiece of the instrument, the mouth as the body or tube, and the nares as the lateral openings.

Dutrochet, 1806, held " that the production of the voice was an active phenomenon, depending upon the vibration of the fibres forming the thyroarytenoidean muscles; and that the vocal tube is supposed to have no influence whatever on the production of tones."

Despiney de Bourg, 1822, stated "that the sounds formed in the glottis undergo at that aperture great variations; to reach the outside they escape through the pharynx, a muscular canal susceptible of experiencing numerous changes, and able, besides, to modify these sounds ; that canal may be compared by its influence to the gliding coulisse of a trombone."

Felix Savart, 1825, says, that "it is easy to comprehend the formation of the voice if we consider the vocal organ, composed of the larynx, the pharynx, and the mouth, like a conical tube in wh?ch the air is brought by a movement analogous to that taking place in the flute-stop of an organ.

Malgaigne, 1831: "The voice is a particular sound produced ordinarily by the passage of the expired air in the aerial tubes." His experiments led him to consider the voice as a reed instrument.

Richeraud, 1833, declared the voice to be "an appreciable sound resulting from the vibrations which the air, sent forth by the lungs, experiences in passing through the glottis." Richeraucl holds a juste milieu among the opinions already given, for he considers the vocal organ at the same time both as a string and a wind instrument.

Bennati, 1833, believes "that it is not the muscles only of the larynx that serve to modulate the sounds in singing, but also those of the os hyoicles, those of the tongue, and those of the superior, anterior, and posterior parts of the vocal pipe, and that without the simultaneous and proportionally combined work of these, the degree of modulation cannot take place."

Dr. James Rush, 1833, says: "All we know is, that the voice is caused by the passage of air through the larynx and cavities of the mouth and nose."

Magendie, 1836 : "We understand by voice the sounds produced in the larnyx at the time the air passes through that organ, be it to enter the wind-

HISTORIC SUMMARY. 25

pipe or to leave it." He makes the vocal organ a reed instrument.

Colunibat, 1838, states : " The voice is an animal sound, living and articulate ; of which the air is the material cause, and the glottis the efficient cause."

Dr. John W. Draper, 1850, says, that "articulation is effected by the motions of the tongue and other portions of the mouth ; sound is produced by the glottis, speech by the mouth."

Miiller, 1851, states, that "in the formation of the voice, the windpipe acts as a wooden pipe of like diameter would do."

Manuel Garcia: "The voice is formed by the periodical compressions and dilations which the air experiences wheu, on reaching the glottis, the latter, by alternate and regular movements, stops or permits its exit."

Dr. John C. Dalton, Jr., 1859: "That when a vocal sound is to be produced, the vocal cords are suddenly made tense, and applied closely to each other so as to diminish very considerably the size of the orifice : and the air driven by an unusually forcible expiration through the narrow opening of the glottis, in passing between the vibrating vocal cords, is itself thrown into vibrations, which produce the sound required."

A. Debay, 1861 : " The voice may be defined as the sonorous vibrations which are produced by the air, expelled by the lungs through the glottis, and escaping through the pharyngo-buccal cavity."

Dr. Ed. Fournie, 1866 : "The voice is a sound produced by a particular reed having walls modifiable under the influence of muscular action ; the vibrating part being furnished by the mucous fold which limits the borders of the glottis. The vibrations are occasioned by the passage of the air through the glottis."

Dr. James Yearsley, 1866: a The term applies properly to the sounds produced by the action of the air on the vocal cords in the larynx."

L. Mandl, 1872: u The air in passing through the glottis is thrown into vibration and a sound called the glottic sound is produced ; this, combined with the sounds produced by the air passing through the pharyngeal cavities, — the pharyngeal sounds, — constitutes what is generally known as the voice."

My ideas regarding the formation of the voice do not differ materially from those given above. The vocal ligaments in a state of rest, are not brought into close juxtaposition, but for the utterance of sound, they are approximated by muscular' action, dependent upon volition, and the vocal ligaments act in the same manner as two membranous lips, which, as the air is forced up

HISTORIC SUMMARY. 27

by the expiratory effort, are thrown into vibration, and thus produce the voice. This phenomenon requires the concourse of a great number of organs ; the walls of the thorax, the lungs, the larynx and trachea, the mouth and nasal fossae. However, the larynx alone essentially belongs to the voice.

Let us now pass from the summary of the various opinions held, concerning the mode of production of the vocal sounds, to the consideration of the anatomy of the individual parts, in order that we may understand clearly and appreciate fully the wonderful delicacy, simplicity, and beauty of the mechanism, which is one, if not the principal, means of communication between man and man, and which therefore affects not only his physical, but also his mental condition.

Chapter III. Anatomy Of The Vocal Apparatus

The organs concerned in the production of vocal sounds are composed of three separate and distinct portions,

1st. The lungs (analogous to the bellows of an organ), and trachea, which furnish and convey the air necessary to produce the vibrations.

2d. The larynx, containing in its interior the vocal cords.

3d. The pharynx, mouth, and nasal anfractuosities, which serve to modify the sounds produced in the larynx.

I. THE LUNGS AND TRACHEA.

The lungs, the organs of respiration proper, are tivo in number, situated side by side in the thoracic cavity, surrounding the heart and occupying almost all the chest, except a very small space to the left of the median line where the heart may be felt to beat against the wall of the chest. They are separated from the abdominal cavity by the

ANATOMY OF THE VOCAL APPARATUS.

i fM W

A The Tongue.

B The Cavity of the Month.

C The Uvula and Soft Palate.

D The Nasal Fossae.

E The Passage communicating with the

Nose.

F The Pharyngeal Cavity.

G The Epiglottis.

IT The Rima Glottis, or Opening of the

Lai-ynx.

/ The Vocal Ligaments, or Corde Vocali.

K The Larynx.

L The Trachea, or Windpipe.

M The Bronchial Tubes.

N The (Esophagus.

P The Spinal Vertebrae.

HYGIENE OF THE VOICE.

Fig. 2.

HUMAN AIR-TUBES.

The mode of distribution of the air-tubes is represented in Fig. 2 (Draper's) : a is the larynx ; b b, the trachea, the upper letter corresponding to the cricoid cartilage ; c, the left bronchus ; d, the right bronchus ; e, /, g, its ramifications in the right lung, j j ; h, i, ramifications of the left bronchus in the left lung, k K

DISTBIBUTION OF CAPILLARIES ON AIR-CELLS OF THE LUNGS.

diaphragm, a sort of muscular membranous partition ; their size varies with the capacity and condition of the chest, the age and sex of the individual, the state of the health, and their condition at the time, whether of expiration or inspiration. They are conical in shape, the apex of the cone being directed upward ; the right lung being shorter, but larger than the left, whose transverse diameter is somewhat shortened by the position of the heart. Their color is a light pinkish tint speckled with black.

The lungs are spongy in structure, and consist of air-vessels, air-cells or vesicles, nerves and blood-vessels, held together by the ordinary packing material of the body, cellular tissue, and are covered by the pleura, a shining membrane which is kept constantly lubricated so that they may move without friction or injury ; the spongy character of the lungs is due to the air-vesicles.

If we examine the respiratory organs of any animal, the lights as they are commonly called, we find that the trachea divides into the bronchi, and these again divide and subdivide, diminishing in size till they become mere capillaries, losing their cylindrical shapes from the great number of air-vesicles (about y^- of an inch in diameter), which open upon their sides, and finally terminate in one of these vesicles. A certain number of vesicles communicate directly with each other, and with a single branch of the bronchial tube, and are separated from neighboring air-cells by partitions of cellular tissue — parenchyma— and thus are formed the lobules of the lungs. We may, therefore, consider the lung as nothing more nor less than a collection of these lobules packed in cellular tissue, held together by the ramifications of the bronchi, which open in the midst of them, and thus put them into communication with the external air, through the air-passages consisting of the trachea or windpipe, the bronchi, and their division.

If by careful dissection a lung be freed from nervous, vascular, and cellular tissue, the bronchi and their ramifications, which will then alone remain, will be found to bear a very close resemblance to a tree with its branches.

Cruveilhier remarks that the size of the lungs, corresponding exactly with the capacity of the thorax, is therefore, like it, subject to variations ; and as, on the one hand, the size of the lung is generally a measure of the energy of respiration, and, on the other, the energy of the respiration is a measure of the muscular strength, it follows, that a capacious chest, coinciding with broad shoulders, is the characteristic of a sanguine temperament and athletic constitution.

The trachea or 'windpipe, which carries the air to and from the lungs, is a cylindrical tube four or five inches in length, situated in front of the oesophagus or gullet — which carries food to the stomach, — extending from the larynx above to the third dorsal vertebra below, where it divides into two tubes, called the right and the left bronchus, which go to the corresponding lung ; then the bronchi continue to subdivide until they become capillaries. The windpipe is formed of from sixteen to twenty cartilaginous rings, connected by ligamentous tissue of an elastic character ; these rings are about two lines in breadth, and form the anterior two-thirds of the tube, but are deficient in the posterior third, which is completed by a muscular structure, whose fibres are placed transversely and which possess much elasticity, to allow for the distention of the oesophagus while the food is on its way to the stomach. The object of the rings is to prevent the falling in of the walls of the trachea during inspiration, and so to allow of the free access of air. The first ring is the largest, and the last is of such a shape as to be adapted to the first rings of the bronchi.