LARYNX.
The larynx is the principal organ of voice. It is situated in the front of the neck, and forms the prominence sometimes called “Adam’s apple”; it also forms a part of the anterior boundary of the pharynx. At the upper part it has the form of a triangular box, with one angle directly in front. It is composed of nine cartilages moved by muscles, and lined with mucous membrane. Six of its cartilages are in pairs; three are single. The three single cartilages are the thyroid, cricoid, and epiglottis; the three pairs are the arytenoid, cuneiform, and cornicula laryngis. The larynx is sometimes called a music-box; from it proceeds the sound called voice.
SIDE VIEW OF THE LARYNX AND TWO RINGS OF THE TRACHEA.
VOCAL CORDS.
Across the larynx are stretched the true vocal cords.
SHAPE OF THE GLOTTIS WHEN AT REST.
THE GLOTTIS DILATED.
GLOTTIS, CLOSED, AND MUSCLES CLOSING IT.
Each cord consists of a band of yellow tissue, covered by mucous membrane.
By means of the action of the muscles of the larynx that connect with the cartilages which enter into its structure, the vocal cords are so adjusted that when the muscles of expiration force the air, which is compressed in the lungs, out between these cords, their edges are set in vibration. This is the beginning of the sound which we call voice, but before it is heard in speech or song it is reinforced by the chambers of resonance.[[1]]
| [1] | For the function of the false, or superior vocal cords, see pp. 68-71, Physical Culture. |
PITCH.
The various degrees of pitch in the compass of the voice depend upon the rate of vibration of the vocal cords. This rate of vibration, the pressure of breath being the same, is caused by the different degrees of tension of the vocal cords. If the vocal cords are drawn thin and short, the pitch will be high; as the tension diminishes, the pitch will be lower. The greater the number of vibrations to the second, the higher will be the pitch. A sound consisting of sixteen vibrations to the second produces the lowest pitch that has been recognized by the human ear as sound; while more than 38,000 vibrations per second have not been heard.
The lowest rate of vibration on record of any voice is about forty-four vibrations per second, while the highest rate in any voice on record is a little over nineteen hundred.
LOUDNESS.
Different degrees of loudness of voice are caused by different degrees of amplitude of the waves of vibration.
THE LUNGS.
The two lungs are the essential organs of respiration; the right lung has three lobes, the left, two. The base of each lung rests upon the convex surface of the diaphragm.
FRONT VIEW OF THE HEART AND LUNGS, AND LARGE BLOOD-VESSELS.
The root of each lung is formed by the bronchus and blood-vessels, which enter the lung a little above the middle of its inner surface, and connect it to the heart and trachea. With the exception of the root, the surface of each lung is free and moves in the cavity of the thorax. The bronchus is one of two tubes which arise from the bifurcation of the trachea. It conducts the air from the trachea to either lung. The bronchial tubes are sub-divisions, or ramifications, of the bronchus and terminate in the air-cells.
MUSCLES OF RESPIRATION.
Inasmuch as voice is vocalized breath, it is important to give attention to respiration.
The principal muscles used in the ordinary movements of inspiration are:—
| I. | Diaphragm. | |
| II. | Levatores costarum. | |
| III. | External intercostals. | |
The principal muscles used in expiration are:—
| I. | Internal intercostals | ||
| with the infracostals. | |||
| II. | Triangularis sterni. | ||
| { Transversalis. | |||
| III. | Abdominal muscles | { Rectus. | |
| { Internal oblique. | |||
| { External oblique. | |||
There are many accessory muscles which aid in violent respiratory movements, both inspiratory and expiratory. All the muscles which elevate the scapula may act through it upon the ribs; the three scalene muscles act directly upon the first rib.
The principal muscles of inspiration may be assisted by the
| I. | Serratus posticus superior. | |
| II. | Serratus magnus. | |
| III. | Pectoralis major. | |
| IV. | Pectoralis minor. | |
The principal muscles of expiration may be aided by the following muscles:—
| I. | Serratus posticus inferior, | |
| II. | Longissimus dorsi, | |
| III. | Sacro lumbalis, | |
and all the muscles which tend to depress the ribs.
THE DIAPHRAGM.
DIAPHRAGM.
The diaphragm separates the cavity of the thorax from the cavity of the abdomen, and constitutes the floor for the heart and lungs to rest upon, and also a close-fitting cover for the contents of the abdomen. Therefore it is evident that the moving of the diaphragm moves the organs which are immediately above and those below it. In reposeful breathing the enlargement of the cavity of the chest is chiefly accomplished by the contraction of the diaphragm. As it contracts it presses upon the abdominal viscera. The abdominal muscles antagonize the diaphragm by pressing back the abdominal viscera, thus causing its ascent as soon as the diaphragm has become relaxed.
As the diaphragm contracts, the air rushes through the nostrils or mouth to fill the lungs. By lifting the ribs the thorax can be sufficiently enlarged to meet ordinary demands for breath; therefore the lungs would not immediately suffer if the diaphragm was not contracted. The principal sufferers in such a case would be the stomach, liver, and intestines, for without this exercise which the contraction of the diaphragm gives them they would not as vigorously perform their functions.
It is taught in many works on physiology that men inhale by means of the contraction of the diaphragm chiefly, while in adult women the diaphragm is exercised little, if any, during respiration. This statement was first given in early physiologies without due warrant from close observation. This idea, having once found its way into a standard work, has continued in successive works until now. This theory is of such vital interest to all that the authority for it should be carefully examined. It is a fact that more women than men breathe wholly by means of elevating and lowering the ribs; it is also a well-observed fact that the healthiest women and the healthiest men breathe alike, with no movement of the upper part of the chest during reposeful respiration. It is only when an unusual amount of air is required that the healthiest men and women ever move the upper part of the chest during respiration; then the diaphragm is exercised vigorously, and the movements of the ribs take place only for the purpose of enlarging the cavity of the thorax beyond what it is possible for the diaphragm alone to accomplish. During the last twenty-five years I have cured hundreds of people, both men and women, of dyspepsia and its attendant weaknesses by teaching them how to exercise the diaphragm in respiration, and in the production of tone. To say nothing of the incorrect way in which women breathe, I find that a majority of men breathe improperly.
The shape of the diaphragm, when it is relaxed, resembles an open umbrella. When the diaphragm is flattened by contraction it no longer retains its dome-like shape, and thus gives greater depth to the thorax.
DIFFERENCE IN THE ACTION OF THE DIAPHRAGM
DURING EXPIRATION OF THE BREATH AND
DURING THE PRODUCTION OF TONE.
During expiration of breath the diaphragm is fully relaxed, while during the production of tone it should be somewhat contracted. In the proper adjustment of the diaphragm and abdominal muscles during voice production, the diaphragm by its contraction resists, to some extent, the pressure caused by the contraction of the abdominal muscles, and thus only gradually yields to the force brought against it by the contraction of these muscles, in consequence of which a firm and steady support is given to the voice.
BREATHING THROUGH THE NOSE.
The question is often asked, “Should one breathe through the nose or through the mouth?” Nature has so constructed the organs of respiration and determined their action that a person in health breathes through the nose, while a person in ill health often breathes through the mouth. By “breathing through the nose,” of course, is meant reposeful breathing. In extraordinary breathing some persons are obliged to breathe through the mouth, but this is always an indication of exhaustion or weakness. Every person should, if possible, maintain the habit of breathing through the nose.
Median Section of Mouth, Nose, Pharynx, and Larynx:—a, septum of nose; below it, section of hard palate; b, tongue; c, section of velum pendulum palati; d, d, lips; u, uvula; r, anterior arch or pillar of fauces; i, posterior arch; t, tonsil; p, pharynx; h, hyoid bone; k, thyroid cartilage; n, crycoid cartilage; s, epiglottis; v, glottis; 1, posterior opening of nares; 3, isthmus faucium; 4, superior opening of larynx; 5, passage into œsophagus; 6, mouth of right Eustachian tube.
ORGANS WHICH REINFORCE VOICE.
The organs that reinforce voice are its resonant chambers, viz.:—
Nares,
Mouth,
Pharynx,
Trachea.
Resonance means resounding or sounding again, and is caused by means of the air conveying the vibrations of one substance to another substance. This is familiarly illustrated in the echo.
There are two classes of resonant chambers; one class is comparatively fixed, and consists of the nares and trachea; the other class may, for convenience, be termed the transient forms of resonance. [[2]]A transient resonant chamber is one that is formed on the instant for a particular purpose, and may be broken as quickly.
Elements of speech are formed by producing a succession of definitely formed but transient molds of resonance.
The pharynx is for the purpose of reinforcing the tone, giving it projection and some assistance in proper direction. All the other transient resonant molds are for the purpose of producing elements of speech.
| [2] | See Tyndall on sound, page 227. |
NARES (Nasal cavities).
The nares are the cavities in the head extending through the nose to the pharynx. The walls of the nares are smooth, and, with their turbinated bones, suggest the inside of a sea-shell.
PHARYNX.
The pharynx is a membranous sac. It has seven openings, the two posterior nares, the two Eustachian tubes, the larynx, the œsophagus, and the isthmus faucium, which is the opening into the mouth.
LARYNX, TRACHEA, AND BRONCHI.
TRACHEA.
The trachea, or windpipe, is a cylindrical tube extending from the lower part of the larynx to where it divides into the bronchi. The interior surface is firm and beautiful.
ORGANS WHICH GIVE RESONANT FORMS TO VOICE.
Lips,
Upper gum,
Hard palate,
Soft palate,
Tongue,
Nares.
Although the quality of the voice produced by the vocal cords of the human being cannot be distinguished from that produced by the vocal cords of the lower animals the organs which resound it give it a distinct quality.
No one of these agents alone molds the tone, but their proper relation to each other constitutes resonant molds as definite as those into which melted ore is cast to give it form and stamp. This proper relationship cannot be secured by exercising the organs in any strictly mechanical way, but only by forming definite ideal tones in the mind and exercising the voice while these ideal tones are firmly fixed as steady objects of thought. If these mental objects drop from the mind at any time during the vocal practice, no mechanical ingenuity can possibly take their places in rightly affecting the voice.
Later in this work, I shall more fully elaborate this point.
RELATION OF THE PROPER USE OF THE
VOICE TO HEALTH.
Many years of observation and study have convinced me that the voice exerts a powerful effect upon the whole physical system. It either builds up the body, sustains its power and adds to its health, or it devitalizes the body and brings a dangerous strain upon the entire system.
The voice cannot be a reporter of the person, mental and physical, without holding the most delicate relations to mind and body. The exercise of the voice subtly and vitally affects the organs that promote health and give life. I could give many illustrations showing that the wrong use of the voice has injured health, and that its right use has promoted health; but if the principles involved in this chapter are fully understood, I need not relate incidents to prove that the voice is a life-giver or a death-dealer, depending entirely upon how it is used.
The Greeks were taught the right use of the voice as a part of their physical, intellectual, and moral culture. In modern times we have neglected voice culture to a very great extent, and have suffered much ill health in consequence.
RELATION OF THE PROPER USE OF THE VOICE TO THE VITAL ORGANS.
EFFECT OF THE VOICE UPON THE LUNGS.
Great wisdom is exhibited in the construction of the human lungs. In the arrangement of the air cells, the greatest possible amount of surface is presented in order that the air may freely enter the blood. The lungs are largely made up of blood vessels, bronchial tubes, and air cells. When a person breathes, the oxygen, entering the lungs through the trachea and the bronchial tubes, penetrates the thin walls of these cells and passes at once into the blood. When the blood enters the lungs it is dark in color, but when it leaves the lungs it is of a light vermilion hue. The oxygen which has been taken into the lungs has wrought this change. So wonderful is this element of nature that some have called it life. If there is an elixir of life in the material world surely it is oxygen, for it has to do minutely and intimately with every power of the human body. The more a person breathes this oxygen as it is mixed in the common air, the more life and power he possesses.
It is essential to perfect health that every avenue to the lungs should be kept open and free, and that the air cells should be kept clear, for if the walls of the cells thicken, oxygen cannot penetrate them. If these cells are not properly filled during respiration, the walls thicken, and substances collect in the cells. If any trouble occurs in the air cells, except for traumatic reasons, it will first be found in the apexes of the lungs. In the production of tone, whether on a low, high, or medium pitch, the vocal cords are drawn so closely together that the air cannot immediately escape from the lungs; therefore, unable to get out readily, it is pressed up into the apexes of the lungs by the expiratory muscles, filling the air cells to the utmost, thus keeping them clear and their walls thin and healthy. In correct singing or speaking, the apexes of the lungs are filled with air. Tubercule seeks devitalized tissue for its development. Therefore tuberculosis usually begins in the apexes of the lungs because they are not kept clear and healthy through proper respiration and vocal exercise. Voice was given to man to make him strong and expressive, to give him life and power.
THE EFFECT OF THE VOICE UPON THE STOMACH.
The stomach is the principal organ of digestion. Out of the nutriment taken into it all the tissues of the body are renewed. It lies under the diaphragm, and is held in place by the abdominal muscles. The stomach is moved during respiration, descending with every inspiration, and rising with every expiration.
In addition to this exercise during the production of tone, the stomach is held firmly between the diaphragm and abdominal muscles. At the close of the tone the muscles which thus hold the stomach relax.
A view of the Organs of Digestion, opened in nearly their whole length; a portion of the œsophagus has been removed on account of want of space in the figure; the arrows indicate the course of substances along the canal: 1, the upper lip, turned off the mouth; 2, its frænum; 3, the lower lip, turned down; 4, its frænum; 5, 5, inside of the cheeks, covered by the lining membrane of the mouth; 6, points to the opening of the duct of Steno; 7, roof of the mouth; 8, lateral half-arches; 9, points to the tonsil; 10, velum pendulum palati; 11, surface of the tongue; 12, papillæ near its point; 13, a portion of the trachea; 14, the œsophagus; 15, its internal surface; 16, inside of the stomach; 17, its greater extremity or great cul-de-sac; 18, its lesser extremity or smaller cul-de-sac; 19, its lesser curvature; 20, its greater curvature; 21, the cardiac orifice; 22, the pyloric orifice; 23, upper portion of duodenum; 24, 25, the remainder of the duodenum; 26, its valvulæ conniventes; 27, the gall-bladder; 28, the cystic duct; 29, division of hepatic ducts in the liver; 30, hepatic duct; 31, ductus communis choledochus; 32, its opening into the duodenum; 33, ductus Wirsungii, or pancreatic duct; 34, its opening into the duodenum; 35, upper part of jejunum; 36, the ileum; 37, some of the valvulæ conniventes; 38, lower extremity of the ileum; 39, ileo-colic valve; 40, 41, cœcum, or caput coli; 42, appendicula vermiformis; 43, 44, ascending colon; 45, transverse colon; 46, 47, descending colon; 48, sigmoid flexure of the colon; 49, upper portion of the rectum; 50, its lower extremity; 51, portion of the levator-ani muscle; 52, the anus.
LIVER.
The inferior or concave surface of the liver, showing its subdivisions into lobes: 1, center of the right lobe; 2, center of the left lobe; 3, its anterior, inferior, or thin margin; 4, its posterior, thick, or diaphragmatic portion; 5, the right extremity; 6, the left extremity; 7, the notch in the anterior margin; 8, the umbilical or longitudinal fissure; 9, the round ligament or remains of the umbilical vein; 10, the portion of the suspensory ligament in connection with the round ligament; 11, pons hepatis, or band of liver across the umbilical fissure; 12, posterior end of longitudinal fissure; 13, 14, attachment of the obliterated ductus venosus to the ascending vena cava; 15, transverse fissure; 16, section of the hepatic duct; 17, hepatic artery; 18, its branches; 19, vena portarum; 20, its sinus, or division into right and left branches; 21, fibrous remains of the ductus venosus; 22, gall-bladder; 23, its neck; 24, lobulus quartus; 25, lobulus Spigelii; 26, lobulus caudatus; 27, inferior vena cava; 28, curvature of liver to fit the ascending colon; 29, depression to fit the right kidney; 30, upper portion of its right concave surface over the renal capsule; 31, portion of liver uncovered by the peritoneum; 32, inferior edge of the coronary ligament in the liver; 33, depression made by the vertebral column.
EFFECT OF VOICE UPON THE LIVER.
The liver is a glandular organ, intended for the secretion of bile from the blood. It is situated under the diaphragm and partially over the stomach; therefore the exercises which produce pressure and relief upon the stomach, exert the same effect upon the liver. That the liver may properly perform its function it is necessary for it to be thus exercised. One cannot speak or sing well without moving the diaphragm, and when this is moved it moves nearly all the organs contained in the trunk of the body, and especially promotes the healthy activity of the lungs, stomach, liver, and intestines.
EFFECT OF THE IMPROPER USE OF THE VOICE UPON THE MUCOUS MEMBRANE.
Mucous membrane lines all those passages by which the internal parts communicate with the exterior, and is continuous with the skin at the various orifices of the surface of the body. The mucous membrane, beginning with the lips, lines the mouth, throat, œsophagus, stomach, and in short, the entire alimentary canal. It also lines the nares, larynx, bronchial tubes, and air cells. It is one because unbroken. Its function is to secrete mucous for the purpose of preventing dryness.
Sympathetic relations exist throughout the whole human system, and especially between different parts of the same organ; if one part of the mucous membrane is injured, another part is as liable to suffer as that immediately injured. If congestion takes place in any part of this mucous membrane, it may cause congestion in some remote part of the membrane, without affecting the intervening parts. There is a certain common misuse of the voice which creates in the pharynx an irritation called “clergyman’s sore throat.” By the law of sympathy, this congestion is likely to be communicated from the pharynx to the mucous membrane of the stomach. It may also attack the mucous membrane of the bronchial tubes and through them affect the lungs.
Although this disease caused by the misuse of the voice is called “clergyman’s sore throat,” it is not confined to clergymen; it prevails to a considerable extent among school teachers, lawyers, and auctioneers. It is dangerous for one to enter upon any form of public speaking without having a sufficient knowledge of the voice to use his own correctly. This is true not merely because it gives power to speak more effectively, but because it enables one to preserve his own health, and thereby prolong his usefulness. “Clergyman’s sore throat” is caused by making too close a chamber of resonance in the pharynx while speaking. This is a confirmed habit with a very large number of persons; in fact, it might almost be said to be a prevailing difficulty, but it does not always cause a sore throat until the voice is more constantly used than it ordinarily is in private life.
A clergyman or others may for years have practised this habit without feeling the effect upon the throat; but as soon as they come to speak steadily for a half hour or more, and that, too, for the purpose of being heard in a large room, begin to realize a huskiness which soon develops into an irritation of the throat.
This finally develops into a congestion, and sooner or later into a cough, which results in the breaking down of the powers of the individual, and if it does not receive immediate and proper attention consumption may be the result. No medicine, however good, can give more than a temporary relief. So long as the cause (which is the misuse of the voice), remains, the difficulty must return. Sometimes “clergyman’s sore throat” is not introduced by huskiness; the first symptom observed is that of dryness or irritation. This is especially true if the voice is characterized by a metallic element. All these evils can be cured by proper vocal education, providing the patient does not wait too long.
CONVOLUTIONS AND FISSURES OF THE OUTER SURFACE OF THE CEREBRAL HEMISPHERE.
RELATION OF THE PROPER USE OF THE VOICE TO THE NERVOUS SYSTEM.
The vocal organs may be said to be tools, and the nerves the workmen appointed to use them.
Nerves are whitish and elastic bundles of fibers, with their accompanying tissues. They transmit nervous impulses between nerve centers and various parts of the animal body.
“Nerves are composed of one or more (sometimes nearly a hundred) nerve fibers, each fiber forming a means of communication between two parts more or less distant from each other.”—Dutton.
The brain is contained in the cranium, and may be said to be the controller of the entire nervous system. From it proceed twelve pairs of cranial nerves.
I. Olfactory, nerve of smell,—distributed in the mucous membrane of the nose.
II. Optic, nerve of sight,—distributes its branches to the eye ball.
III. Motor oculi,—motor of the eye.
IV. Patheticus,—assists in moving the eye.
V. Trigeminus,—nerve of sensation, motion, and taste.
VI. Abducens,—assists the movements of the eye.
VII. Facial (or nerve of expression),—moves the face, ear, palate, and tongue. By means of this nerve the tongue is directly connected with the brain, and receives its impulse of action therefrom.
VIII. Auditory,—nerve of hearing.
IX. Glosso-pharyngeal, nerve of sensation and taste,—it is distributed to the back of the tongue, middle ear, tonsils, and pharynx.
X. Pneumogastric,—the auriculo-laryngo-pharyngo-œsophago-tracheo-pulmono-cardio-gastro-hepatic nerve. It is a nerve of sensation and motion, probably receiving its motor influence from its spinal accessory.
XI. Spinal accessory furnishes motor power to the pneumogastric.
XII. Hypo-glossal,—motor of the tongue. It communicates with the pneumogastric and sympathetic nerves.
DIAGRAM OF THE FIRST SIX CRANIAL NERVES, WITH THEIR CHIEF BRANCHES OF DISTRIBUTION.
DIAGRAM OF THE LAST SIX CRANIAL NERVES, WITH THEIR CHIEF BRANCHES OF DISTRIBUTION.
My principal object in writing of the relation of the voice to the nervous system is to show anatomical and physiological reasons for denominating the voice the reporter of the states of mind.
We have before us the names of the nerves which connect the organs of speech with the organ of thought. Through some of the cranial nerves the mind immediately discharges its impulses upon certain organs, both consciously and subconsciously. This is illustrated by the motor occuli, patheticus, and abducens, which move the eye sometimes consciously and sometimes subconsciously. This shows that these nerves may, and often do, act upon the eye, without any conscious plan or purpose on the part of the individual.
The mind often manifests, through the cranial nerves, states of mind of which the person is unconscious. While consciousness is the power by which one knows his own states of mind, there is no proof that consciousness takes note of all one’s states of mind. The proof that it does not is found in the fact that people, through involuntary acts, often manifest mental activities of which they are unconscious. Spontaneous expression is truest.
The facial nerve causes the muscles of the face to portray the thoughts and feelings of the soul more truthfully than any artist could delineate them with pencil and brush. Before we can properly teach vocal culture and oratorical expression we must understand the principle of spontaneous manifestation by means of cranial nerves as distinct from purposeful forms of expression. The facial nerve not only acts as a motor of expression through the face, causing it to reveal thought and emotion, but acts in the same manner upon the tongue, causing it to form and modulate tones in song and speech.
Again note the nature of the hypo-glossal cranial nerve, which is not only a motor of the tongue, causing it to act spontaneously, but is distributed also to the muscles of the neck which are concerned in the movements of the larynx. The purpose of this distribution is probably to associate the action of the tongue with that of the larynx which is necessary for articulate speech. All the motions of the tongue are performed through the medium of these nerves.
The drawing exhibits the cerebral connection of all the cerebral nerves except the first. It is from a sketch taken from two dissections of this part. D. Posterior optic tubercle. The generative bodies of the thalamus are just above it. E. Cerebellum. H. Spinal cord. I. Tuber cinereum. K. Optic thalamus divided perpendicularly. W. Corpus restiforme. X. Pons Varolii. b b. Optic nerves: this nerve is traced on the left side back beneath the optic thalamus and round the crus cerebri. It divides into four roots; the first (g g) plunges into the substance of the thalamus, the next runs over the external geniculate body and surface of the thalamus, the third goes to the anterior optic tubercle, the fourth runs to D, the testis or posterior optic tubercle. C. Third pair common oculo-muscular, arising by two roots like the spinal roots of the spinal nerves, the upper from the gray neurine of the locus niger, the lower from the continuation of the pyramidal columns in the crus cerebri and Pons Varolii, p t. d, Fourth pair, apparently arising from the inter-cerebral commissure (I c), but really plunging down to the olivary tract (o t) as it ascends to the optic tubercles. e m. Motor or non-ganglionic root of the fifth pair, arising from the posterior edge of the olivary tract. e. Sensory root of the fifth pair running down between the olivary tract and restiform body to the sensory tract. f. Sixth pair, or abducens, arising from the pyramidal tract. g. Seventh pair, facial nerve, or portio dura, arising by an anterior portion from the olivary tract and by a posterior portion from the cerebellic fibers of the anterior columns as they ascend on the corpus restiforme, W. h. Eighth pair, portio mollis, or auditory nerve, with its two roots embracing the restiform body. i. Ninth pair, or glosso-pharyngeal; and j. Tenth pair, or par vagum, plunging into the restiform ganglion. J J. Fibers of the optic nerve plunging into the thalamus; immediately below these letters is the corpus geniculatum externum. k. Eleventh pair, or lingual nerve; the olivary body has been nearly sliced off and turned out of its natural position; some of the filaments of the lingual nerve are traced into the deeper portion of the ganglion, which is left in its situation; others which are the highest are evidently connected with the pyramidal tract.
The course and distribution of the Hypoglossal or Ninth pair of nerves; the deep-seated nerves of the neck are also seen: 1, the hypoglossal nerve; 2, branches communicating with the gustatory nerve; 3, a branch to the origin of the hyoid muscles; 4, the descendens noni nerve; 5, the loop formed with the branch from the cervical nerves; 6, muscular branches to the depressor muscles of the larynx; 7, a filament from the second cervical nerve, and 8, a filament from the third cervical, uniting to form the communicating branch with the loop from the descendens noni; 9, the auricular nerve; 10, the inferior dental nerve; 11, its mylohyoidean branch; 12, the gustatory nerve; 13, the chorda tympani passing to the gustatory nerve; 14, the chorda tympani leaving the gustatory nerve to join the submaxillary ganglion; 15, the submaxillary ganglion; 16, filaments of communication with the lingual nerve; 17, the glosso-pharyngeal nerve; 18, the pneumogastric or par vagum nerve; 19, the three upper cervical nerves; 20, the four inferior cervical nerves; 21, the first dorsal nerve; 22, 23, the brachial plexus; 24, 25, the phrenic nerve; 26, the carotid artery; 27, the internal jugular vein.
The study of the functions of the cranial nerves convinces me that the state of mind which conceives a tone acts upon the organs of speech through the cranial nerves in a way to give vocal expression. In perfect expression the conception and the expression are absolutely synchronous.
RELATION OF PITCH TO RESONANCE.
In the production of a good tone there is an exact relation between pitch and resonance. This relation is provided for in nature and a disobedience to it brings an unpleasant quality into the voice. This is true in both speech and song, for the speaking and singing voices rest upon the same fundamental principles. Speech is one application or use of the voice, song is another. The voice of true speech is as melodic as the voice of song. There are, however, many persons who use their voices better when they sing than when they speak, while others use their voices better in speaking than in singing.
There is a difference between tone and noise. Voice is produced by a succession of vibrating waves of air. In a musical tone the waves are regular in their succession; in noise they are irregular.
Resonance, or echo, is produced by the universal law of reflex action which manifests itself in light, sound, etc. How interesting and delightful is the echo! It makes the mountains, like the morning stars, sing together for joy. Listen to a thunder storm among the mountains. There is a sudden explosion, then a silence, as the vibrating waves of mighty amplitude pass over the valley to wake the voice of the mountain beyond, which, standing like a sentinel on guard, speaks in thunder tones to the next, and that repeats the sublime echo until all the mountains join in the chorus, answering back to the heavens. This law of sympathy, undulating from mountain to mountain, so inspired the Greeks that they said the gods spoke to each other from mountain peak to mountain peak.
Every pitch in the human voice has its corresponding chamber of resonance, formed by the nares, by the trachea, by the pharynx, or by the mouth, and sometimes by more than one of these. The transient resonant chambers are formed by the adjustment of the lips, and by the relation of the tongue to the upper gum, the hard palate, the soft palate, and the pharynx. With the exception of the pharynx, these and the nasal forms constitute the resonant chambers which produce the different elements of speech in our language. The tone, though smooth when it leaves the vocal cords, may be made harsh by the transient resonant chambers. The nares resound different intervals of the scale in different portions of their length, never resounding two intervals in the same portion.
The cultivation of the voice is produced, first, through perfecting the forms of the transient chambers of resonance; second, through establishing perfect freedom and regularity in the action of the vocal cords; third, through developing the rhythmic impulses of the tone. No person ever speaks continuously in a perfect monotone; the pitch is constantly changing with the varying thoughts; as the pitch changes, the resonant chambers change the quality. Nature, unhindered, never reports the same quality on two different degrees of pitch. It is not that the individual, while speaking, intends to change the quality; but nature has so arranged the vocal organs and so determined the laws of acoustics, that unless the voice be interfered with by wrong mental determination, she herself changes the quality as the voice rises or falls.
It is a law of acoustics that a low pitch is resounded in a comparatively large resonant chamber; a high pitch in a comparatively small one. A simple and instructive experiment in illustration of this principle is this: Take a large bottle, strike a C tuning fork, hold it over the empty bottle, and no sound will be heard. The bottle does not respond, because the cavity is too large for the pitch of the fork. If water is poured into the bottle, the air column inside thereby being shortened until the proper sized chamber is formed, by then holding the high-pitched tuning fork over it, the sound of the fork will be resounded by the resonant chamber and the tone will burst forth quite loudly. Use any number of tuning forks, each on a different key, and a resonant chamber can thus be made which will resound each fork.
I once tried an experiment with two tuning forks which were fastened to sounding boxes and which had been tuned to exactly the same pitch. I struck one fork and stopping its vibration, the sound of the other, vibrating responsively, was distinctly heard. The same result was achieved when one of the tuning forks was placed in a remote part of the room. I also placed the fork upon the piano, struck it, and the string of the same pitch, in connection with its overtones, responded. In order that any resonant cavity may resound, the pitch that belongs to that cavity must be struck. Every room in a house, in consequence of its size, its form, and the material of which it is constructed, resounds to a certain pitch. Sometimes in the course of conversation the globe of a chandelier in the room resounds. This is because the pitch which is agreeable to its size, form, and substance is struck.
OVERTONES.
Overtones are tones above in pitch, but harmonic with the fundamental tone. They are caused by the vibration of the aliquot parts of a string as distinct from that of its whole length. These parts being shorter vibrate with greater rapidity, thereby giving a higher pitch than the fundamental note, though in perfect harmony with it. An overtone can be discovered by holding near one of the vibrating aliquot parts a chamber of the right size, form, and substance to reinforce the tone of one of these parts. This resonance would be loud enough to be distinguished from the fundamental tone.
The vocal cords act in like manner with the string described, and produce fundamental tones and overtones. In the vocal mechanism which produces the human voice, the resonant chambers are so graded in size as to correspond exactly with the fundamental note and all its overtones; therefore, an overtone as distinct from the fundamental tone is never heard, but reveals its presence only by enriching the voice.