A Treatise on Physiology and Hygiene Part 25

108. The removal of ear-wax is generally unnecessary; for, as we have before seen, Nature provides that the excess of it shall become dry, and then spontaneously fall out in the form of fine scales. The danger from the introduction of solid implements into the outer ear is chiefly found in the fact that the membrane which lies at the bottom of it is very fragile, and that any injury of it is liable to be permanent, and to permanently impair the hearing of the injured ear.

QUESTIONS FOR TOPICAL REVIEW.

_Give as full statements as you can on the following subjects_:

1. Production of sensation 177, 178 2. Variety of sensations 178, 179 3. General sensibility 179, 180 4. The sensation of pain 180 5. The uses of pain 180, 181, 182 6. Special sensation 182, 183 7. Organs of touch 183, 184 8. The sense of touch 184, 185, 186 9. The delicacy of touch 186, 187 10. Sensations of temperature and weight 187, 188 11. The organ of taste 188, 189 12. The sense of taste 189, 190 13. Relations of taste, etc. 190, 191 14. Influence of education, etc. 191, 192 15. The sense of smell 192, 193 16. The nerve of smell 193, 194 17. Uses of the sense of smell 194, 195 18. The sense of sight 196, 197 19. Light, and the optic nerve 197, 198 20. The organ of sight 198, 199 21. The orbits 199 22. The eyelids 200, 201 23. The lachrymal fluid 201, 202, 203 24. The eyeball 203, 204 25. The iris 205, 206 26. The retina 206, 207, 208, 209 27. The crystalline lens 209, 210 28. Uses of the lens 210, 211, 212 29. Long and short sight 212, 213 30. Function of accommodation 213, 214 31. Old sight, or presbyopia 215 32. Hearing and sound 215, 216, 217 33. The external ear 217, 218, 219 34. The middle ear 219-222 35. The internal ear 222, 223, 224 36. Protection of the sense of hearing 224, 225, 226

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CHAPTER XI.

THE VOICE.

_Voice and Speech--The Larynx, or the Organ of the Voice--The Vocal Cords--The Laryngoscope--The Production of the Voice--The Use of the Tongue--The different Varieties of Voice--The Change of Voice--Its Compa.s.s--Purity of Tone--Ventriloquy._

[Sidenote: 1. The uttering of sounds by animals? How produced?]

1. VOICE AND SPEECH.--In common with the majority of the n.o.bler animals, man possesses the power of uttering sounds, which are employed as a means of communication and expression. In man, these sounds const.i.tute the voice; in the animals, they are designated as the cry. The song of the bird is a modification of its cry, which is rendered possible from the fact that its respiratory function is remarkably active. The sounds of the animals are generally, but not always, produced by means of their breathing organs.

Among the insects, they are sometimes produced by the extremely rapid vibrations of the wings in the act of flight, as in the case of the musquito; or they are produced by the rubbing together of hard portions of the external covering of the body, as in the cricket. Almost all kinds of marine animals are voiceless. The tambour-fish and a few others have, however, the power of making a sort of noise in the water.

[Sidenote: 2. The evidence of man's superior endowment? What is stated of the idiot? Parrot? Raven?]

2. But man alone possesses the faculty of speech, or the power to use articulate sounds in the expression of ideas, and in the communication of mind with mind. Speech is thus an evidence of the superior endowment of man, and involves the culture of the intellect. An idiot, while he {228} may have complete vocal organs and full power of uttering sounds or cries, is entirely incapable of speech; and, as a rule, the excellence of the language of any people will be found to be proportional to their development of brain. Man, however, is not the only being that has the power to form articulate sounds, for the parrot and the raven may also be taught to speak by rote; but man alone attaches meaning to the words and phrases he employs.

[Sidenote: 3. Speech and hearing? A deaf child? Person having "no ear for music?" Impaired hearing? What do the examples show?]

3. Speech is intimately related to the sense of hearing. A child born deaf is, of necessity, dumb also; not because the organs of speech are imperfect, for he can utter cries and may be taught to speak, and even to converse in a rude and harsh kind of language; but because he can form no accurate notion of sound. And a person, whose hearing is not delicate, or as it is commonly expressed, who "has no ear for music," cannot sing correctly. A person who has impaired hearing commonly talks in an unnaturally loud and monotonous voice. These examples show the necessary relation of intelligence and the sense of hearing with that form of articulate voice, which is termed speech.

[Sidenote: 4. Organ of the voice? Where situated? Of what is its framework composed?]

4. THE ORGAN OF THE VOICE.--The essential organ of the voice is the Larynx.

This has been previously alluded to in its relation to the function of respiration; and, in the chapter on that subject, are figured the front view of that organ (Fig. 35), and its connection with the trachea, tongue, and other neighboring parts (Fig. 38). It is situated at the upper part of the neck, at the top of the trachea, or tube by which air pa.s.ses into and out of the lungs. The framework of the larynx is composed of four cartilages, which render it at once very strong and sufficiently flexible to enable it to move according to the requirements of the voice. {229}

[Ill.u.s.tration: FIG. 55. SECTION OF THE LARYNX AND TRACHEA.

A, The Epiglottis. B, The Thyroid Cartilage. C, Arytenoid Cartilage.

D, Ventricle of the Larynx. E, Cricoid Cartilage. F, Right Vocal Cord.

H, The Trachea.]

[Sidenote: 5. Names, formation, and situation of the cartilages?]

5. The names of the cartilages are (1) the _thyroid_, which is a broad thin plate, bent in the middle and placed in the central line of the front part of the neck, where it is known as the _pomum Adami_, or Adam's apple (Fig.

55, B), and where it may be felt moving up and down with each act of swallowing; (2) the _cricoid_, which is shaped like a seal ring, with the broad part placed posteriorly (Fig. 55, E). At the top of the cricoid cartilage are situated the two small _arytenoid_ cartilages, the right one of which is shown in Fig. 55, C. These latter little organs are much more movable than the other two, and are very important in the production of the voice. They have a true ball and socket joint, and several small muscles which contract and relax with as perfect regularity and accuracy as any of the larger muscles of the body.

[Sidenote: 6. Lining of the interior of the larynx? The epiglottis?]

6. The interior of the larynx is lined with a very sensitive mucous membrane, which is much more closely adherent to the parts beneath than is usually the case with membranes of this description. The epiglottis (A), consisting of a single leaf-shaped piece of cartilage, is attached to the front part of the larynx. It is elastic, easily moved, and fits accurately over the entrance to the air-pa.s.sages below it. Its office is to guard these delicate pa.s.sages and the lungs against the intrusion of food and other foreign {230} articles, when the act of swallowing takes place. It also a.s.sists in modifying the voice.

[Sidenote: 7. Where are the vocal cords? The false cords? The true cords?]

7. THE VOCAL CORDS.--Within the larynx, and stretched across it from the thyroid cartilage in front to the arytenoid cartilages behind, are placed the two sets of folds, called the vocal cords. The upper of these, one on each side, are the false cords, which are comparatively fixed and inflexible. These are not at all essential to the formation of vocal sounds, for they have been injured, in those lower animals whose larynx resembles that of man, without materially affecting their characteristic cries. Below these, one on each side, are the true vocal cords (Fig. 55, F), which pursue a similar direction to the false cords, namely, from before backward. But they are composed of a highly elastic, though strong tissue, and are covered with a thin, tightly-fitting layer of mucous membrane. Their edges are smooth and sharply defined, and when they meet, as they do in the formation of sounds, they exactly match each other.

[Sidenote: 8. Where is the ventricle of the larynx? The essentials to the formation of the tones and modulation of the voice?]

8. Between the true and false vocal cords is a depression on each side, which is termed the ventricle of the larynx (Fig. 55, D). The integrity of these true cords, and their free vibration, are essential to the formation of the tones and the modulation of the natural voice. This is shown by the fact that, if one or both of these cords are injured or become diseased, voice and speech are compromised; or when the mucous membrane covering them becomes thickened, in consequence of a cold, the vocal sounds are rendered husky and indistinct. When an opening is made in the throat below the cords, as not infrequently happens in consequence of an attempt to commit suicide, voice is impossible except when the opening is closed by external pressure. {231}

[Ill.u.s.tration: FIG. 56. A VIEW OF THE VOCAL CORDS BY MEANS OF THE LARYNGOSCOPE.]

[Sidenote: 9. Variation in the interval between the true cords of the voice? Experiment with the mirror?]

9. The interval or s.p.a.ce between the true cords of the voice is constantly varying, not only when their vocal function is in exercise, but also during the act of respiration. Every time the lungs are inflated, the s.p.a.ce increases to make wide the entrance for the air; and diminishes slightly during expiration. So that these little cords move gently to and fro in rhythm with the expansion and contraction of the chest in breathing. These movements and others may be seen to take place, if a small mirror attached to a long handle be placed back into the upper part of the throat; the handle near the mirror must be bent at an angle of 45, so that we may look "around the corner," so to speak, behind the tongue. The position which the mirror must a.s.sume will be understood by reference to Fig. 38. A view of what may be seen under favorable circ.u.mstances, during tranquil inspiration is represented in Fig. 56. The vocal cords are there shown as narrow, white bands, on each side of the central opening, and since the image is inverted, the epiglottis appears uppermost. The rings partly seen through the opening belong to the trachea. This little mirror is the essential part {232} of an instrument, which is called the laryngoscope, and, simple as it may seem, it is accounted one of the most valuable of the recently invented appliances of the medical art.

[Sidenote: 10. The formation of true vocal tones?]

10. THE PRODUCTION OF THE VOICE.--During ordinary tranquil breathing no sound is produced in the larynx, true vocal tones being formed only during forcible expiration, when, by an effort of the will, the cords are brought close together, and are stretched so as to be very tense. The s.p.a.ce between them is then reduced to a narrow slit, at times not more than 1/100 of an inch in width; and the column of expired air being forced through it causes the cords to vibrate rapidly, like the strings of a musical instrument.

Thus the voice is produced in its many varieties of tone and pitch; its intensity, or loudness, depending chiefly upon the power exerted in expelling the air from the lungs. When the note is high, the s.p.a.ce is diminished both in length and width; but when it is low, the s.p.a.ce is wider and longer (Fig. 57, B, C), and the number of vibrations is fewer within the same period of time.

[Ill.u.s.tration: FIG. 57. THE DIFFERENT POSITIONS OF THE VOCAL CORDS.

A, The position during inspiration. B, In the formation of low notes. C, In the formation of high notes.]

[Sidenote: 11. To what is the personal quality of the voice mainly due?

What aids are there?]

11. The personal quality of the voice, or that which enables us to recognize a person by his speech, is mainly due to the peculiar shape of the throat, nose, and mouth, and {233} the resonance of the air contained within those cavities. The walls of the chest and the trachea take part in the resonance of the voice, the air within them vibrating at the same time with the parts above them. This may be tested by touching the throat or breast-bone, when a strong vocal effort is made. The teeth and the lips also are important, as is shown by the unnatural tones emitted by a person who has lost the former, or by one who is affected with the deformity known as "hare-lip." The tongue is useful, but not indispensable to speech; the case of a woman is reported, from whom nearly the whole tongue had been torn out, but who could, nevertheless, speak distinctly and even sing.

[Sidenote: 12. Varieties of voice? The baritone? The voice in early youth?]

12. THE VARIETIES of voice are said to be four in number; two, the ba.s.s and tenor, belonging to the male s.e.x; and two, the contralto or alto, and soprano, peculiar to the female. The baritone voice is the name given to a variety intervening between the ba.s.s and tenor. In man, the voice is strong and grave; in woman, soft and high. In infancy and early youth, the voice is the same in both s.e.xes, being of the soprano variety: that of boys is both clear and loud, and being susceptible of considerable training, is highly prized in the choral services of the church and cathedral. At about fourteen years of age the voice is said to change; that is, it becomes hoa.r.s.e and unsteady by reason of the rapid growth of the larynx. In the case of the girl, the change is not very marked, except that the voice becomes stronger and has a wider compa.s.s; but in the boy, the larynx nearly doubles its size in a single year, the vocal cords grow thicker, longer, and coa.r.s.er, and the voice becomes masculine in character. During the progress of this change, the use of the voice in singing is injudicious.

[Sidenote: 13. The range of the voice? Result of careful training of the vocal organs?]

13. The ordinary range of each of the four varieties of {234} the voice is about two octaves; but this is exceeded in the case of several celebrated vocalists. Madame Parepa-Rosa has a compa.s.s of three full octaves. When the vocal organs have been subjected to careful training, and are brought under complete control of the will, the tension of the cords become exact, and their vibrations become exceedingly precise and true. Under these circ.u.mstances the voice is said to possess "purity" of tone, and can be heard at a great distance, and above a mult.i.tude of other sounds. The power of a pure voice to make itself heard was recently exemplified in a striking manner: at a musical festival held in an audience-room of extraordinary size, and amid an orchestra of a thousand instruments and a chorus of twelve thousand voices, the artist named above also sang; yet such was the purity and strength of her voice that its notes could be clearly heard rising above the vast waves of sound produced by the full accompaniment of chorus and orchestra.

[Sidenote: 14. The production of the articulate sounds? What experiment is mentioned?]

14. In the production of the articulate sounds of speech, the larynx is not directly concerned, but those sounds really depend upon alterations in the shape of the air-pa.s.sages above that organ. That speech is not necessarily due to the action of the larynx is proven by the following simple experiment. Let an elastic tube be pa.s.sed through the nostril to the back of the mouth. Then, while the breath is held, cause the tongue, teeth, and lips to go through the form of p.r.o.nouncing words, and at the same time, let a second person blow through the tube into the mouth. Speech, pure and simple, or, in other words, a whisper is produced. Still further continue the experiment, while permitting vocal sounds to be made, and there will be produced a loud and whispering speech at the same moment; thus showing that voice and speech are the result of two distinct acts. Sighing, in like manner, is {235} produced in the mouth and throat; if, however, a vocal sound be added, the sigh is changed into a groan.

[Sidenote: 15. What is ventriloquism? Indication of the original meaning of the word? How are the ventriloquous sounds produced?]

15. VENTRILOQUISM is a peculiar modification of natural speech, which consists in so managing the voice that words and sounds appear to issue, not from the person, but from some distant place, as from the chimney, cellar, or the interior of a chest. The original meaning of the word ventriloquism (that is, speaking from the belly), indicates the early belief that this mode of speech was dependent upon the possession and use of some special organ besides the larynx and mouth; but at the present time, it is known that it is produced by these organs alone, and that the sources of deception consist on the part of the performer, in the dexterous management of the voice, together with a talent for mimicry; and, on the part of the auditory, in the liability of the sense of hearing to error in respect to the direction of sounds. The ventriloquist not only seems to "throw his voice," as it is said, or simulates the sound as it usually appears at a distance with but little motion of the lips and face, but he imitates the voices of an infant and of a feeble old man, of a drunken man disputing with an exasperated wife, the broken language of a foreigner, the cry of an animal in distress, demonstrating that the performer must be proficient in the art of mimicry. Ventriloquism was known to the ancient Romans and Greeks; and it is thought that the mysterious responses that were said to issue from the sacred trees and shrines of the oracles at Dodona and Delphi, were really uttered by priests who had the power of producing this form of speech.

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