CHAPTER VI.

1.(a) Inspiring slowly, with counting.(b) Holding.(c) Expiring slowly, with counting.2. The same, holding longer.3. The same, with shorter inspiration and longer expiration. Gradually diminish first and lengthen last.4. Breathing through open lips.5. Exercises to strengthen diaphragm.6. Exercises to improve shape of chest and strengthen muscles.7. Exercises to strengthen abdominal muscles.

Thelarynx, or voice-box, is not the sole voice-producing apparatus, as is often supposed, but it is of great, possibly the greatest, importance. In describing the parts of this portion of the vocal mechanism the author deems it wiser to use the terms commonly employed by anatomists and physiologists, as others are awkward and inadequate. Moreover, there is this great advantage in learning the technical names of structures, that should the reader desire to consult a special work on anatomy in reference to this or other important organs, he will find in use the same terms as he has himself already learned. Such are, as a matter of fact, not difficult to learn or remember if one knows their derivation or other reason for their employment. All the muscles of the larynx have names which are not arbitrary but based on the names of the structures to which they are attached, so that one has but to know their connections and the names of the solid structures, which are few, to have a key to the whole nomenclature.

When one is not using the voice the larynx is simply a part of the respiratory apparatus, but when one phonates this organ assumes a specialfunction for which specific structures are essential. As sound is caused by vibrations of the air, and these may be set up by vibrations of the vocal cords, it may with absolute correctness be said that the whole larynx exists for the vocal bands so far as voice-production is concerned. Such a view renders the study of the larynx much more interesting and rational; one is then engaged in working out that solution of a problem which Nature has accomplished.

The vocal cords, we can conceive, might be either relaxed or tightened, and lengthened or shortened, or both, and beyond that we can scarcely understand how they might have been modified so as to be effective in the production of sounds of different pitch. As a matter of fact, these are the methods Nature has employed to accomplish her purpose. For each vocal cord one fixed point, and only one, is required. We know of only one method in use by Nature to cause movement in living structures—viz., contraction, and muscle is the tissue which above all others has that property; hence the movements of the vocal cords are brought about by muscles. But both for the attachment of the muscles and the vocal cords themselves solid, relatively hard structures are required. Bone would prove too unyielding, but cartilage, or gristle, meets the case exactly. The entire framework of the larynx—its skeleton, so to speak—is made up of a series of cartilages unitedtogether so as to ensure sufficient firmness with pliability.

The cartilages have been named from their shape, as that appealed to the original observers, and the terms employed are of Greek origin. The largest and strongest is thethyroid(thureos, a shield) cartilage, which resembles somewhat two shields put together in front without any visible joint, and open behind but presenting a strongly convex surface externally, in front and laterally. "Front" (anterior) and "back" (posterior) always refer in anatomy to the subject described, and not to the observer's position. In observing another's larynx the subject observed and the observer naturally stand front to front, and it is impossible to see or touch the back of the larynx as it is covered behind by the other structures of the neck.

This thyroid, the largest of the cartilages, is attached to the hyoid or tongue bone above by a membrane, so that the whole larynx hangs suspended from this bone by a membrane, though not by it alone, for muscles are attached to it which also serve for its support. It is of practical importance to remember that the larynx is free to a very considerable extent, otherwise it would go ill with the voice-producer in the vigorous use of the voice, not to mention the advantages of mobility as well as pliability in the movements of the neck generally.

Fig. 20

Fig. 20 (Spalteholz). Shows the thyroid cartilage above and the cricoid below both viewed from the side. The anterior surface is turned toward the right.

Fig. 21

Fig. 21 (Spalteholz). A front view ofFig. 20.

Fig. 24

Fig. 24 (Spalteholz). Shows the arytenoid cartilages, the most important of all the cartilages of the larynx, inasmuch as to the part termed "vocal process" the vocal band is attached on each side. The movements of the vocal bands are nearly all determined by the movements of these cartilages, which have a swivel-like action. In the above the front surfaces are turned toward each other.

Thecricoid(krikos, a signet-ring) is the cartilage next in size. It is situated below the thyroid cartilage, with which it is connected by a membrane, the crico-thyroid. The wider part of this signet-ring is situated behind, where it affords attachment to large muscles. It also furnishes a base of support for two very important structures, thearytenoid(arutaina, a ladle) cartilages. As the vocal bands are attached behind to them, and as they have a large degree of mobility, they are from a physiological point of view the most important of all the solid structures of the larynx.

There are two pairs of small bodies, thecartilages of Santorini, orcornicula laryngis, surmounting the arytenoids, and thecuneiform, orcartilages of Wrisberg, situated in the folds of mucous membrane on each side of the arytenoids; but these structures are of little importance.

The whole of the inner surface of the larynx is lined with mucous membrane, though that covering over the true vocal bands is very thin, and so does not cause them to appear red like the false vocal bands, which are merely folds of the mucous membrane. However, the true vocal bands may become red and thickened when inflamed, because of this same mucous membrane, which, though ordinarily not visible to the eye, becomes so when the condition referred to is present; for inflammation is always attended by excess in the blood supply, with a prominence of the small blood-vessels resulting in a corresponding redness. Thesame thing happens, in fact, as in inflammation of the eyes or the nose, both of which are more open to observation. Bearing this in mind one can readily understand why in such a condition, which is often approached if not actually present in the case of "a cold," the voice becomes so changed. Such vocal bands are clumsy in movement, as the arms or any other part would be if thus swollen. The plain remedy is rest, cessation of function—no speaking, much less attempts at singing. Like the nose the larynx, and especially the vocal bands, may be catarrhal, and such a condition may call for medical treatment before the speaker or singer can do the most effective vocal work.

While thefalse vocal bandshave little or nothing to do with phonation directly, they do serve a good purpose as protectors to the more exalted true vocal bands. When coughing, swallowing, vomiting, holding the breath tightly, etc., these folds of mucous membrane close over the true bands, often completely, and thus shut up for the moment the whole of that space between the bands known as the glottis, or glottic chink, to which reference was made in a previous chapter as the space through which the air finally gains access to the lungs.

Fig. 25

Fig. 25 (Spalteholz). A view of the larynx from behind. Several of the muscles are well shown, of which the two indicated above are of the most importance. The arytenoideus proprius tends to bring the cartilages from which it is named, and therefore the vocal bands, toward each other; while the posterior crico-thyroid, from its attachments and line of pull, tends to separate these and lengthen the vocal bands.

Fig. 26

Fig. 26 (Spalteholz). Showing structures as indicated above. The mucous membrane, that naturally covers all parts within the vocal mechanism, has been dissected away to show the muscles.

Fig. 27

Fig. 27 (Spalteholz). Showing the parts indicated above; and of these the crico-thyroid muscle is to be especially observed. The oblique (especially so in the posterior part) direction of its fibres is evident, so that when it contracts, it must pull up the ring cartilage in front, and so tilt back its hinder portion and with it the arytenoid cartilages, and so lengthen and tense the vocal bands, as in the utterance of low tones.

The true vocal cords (which, because of having some breadth and being rather flat, are better termed vocal bands) are composed largely ofelastic tissue. The reader may be familiar with thisstructure, which is often to be found in the portions of the neck of the ox that the butcher sells as soup beef. It is yellow in color, and stretching it has furnished many a boy with amusement. It is so unmanageable when raw that when it falls to the dog he usually bolts it, the case being otherwise hopeless. Such elastic tissue is, however, the very material for the construction of vocal bands, as they require to be firm yet elastic.

Fig. 28

Fig. 28 (Spalteholz). A back (posterior) view of the larynx, etc. Note how the arytenoid cartilages rest on the cricoid; how the epiglottis overhangs, as its name implies, the glottis; and that the posterior part of the windpipe is closed in by soft structures, including (unstriped) muscle.

It is important to remember the relative position of parts and to bear in mind that most of the laryngeal structures are in pairs. To this last statement the thyroid and cricoid cartilages and the epiglottis are exceptions, being single.

Of theepiglottis, a flexible cartilage, it is necessary to say little, as its function in voice-production, if it have any, has never been determined. It hangs as a flexible protective lid over the glottis, and food in being swallowed passes over and about it. It no doubt acts to keep food and drink out of the larynx, yet in its absence, in some cases, owing to disease, no very great difficulty was experienced, probably because certain muscles acted more vigorously than usual and tended to close up the glottic chink.

The following simple diagram will, it is hoped, make the relative position of parts plain so far as the anterior (front) attachments of parts to the thyroid cartilage are concerned. It will be understood that the inner anterior surface is meant, andthat by "middle line" is intended the middle line of the body, the imaginary vertical diameter passing like a plumb-line from the middle plane of the head, let us suppose, downward just in front of the larynx.

Fig. 29

Fig.29.

The angle made above and in front where the two wings of the thyroid cartilage meet is termedAdam's apple(Pomum Adami), and in some cases, mostly males, is very prominent. Adam's apple has in itself, however, no special significance in voice-production.

The little concavity between the false vocal bands above and the true vocal bands below is termed theventricle of the larynx. It allows of more space for the free movements of the bands, especially those more important in voice-production.

The vocal bands are attached behind to the projecting angle of the base of the arytenoid cartilage, which is itself somewhat triangular in shape, the base of the triangle being downward and resting on the upper and posterior (back) surface of the cricoid cartilage, with which it makes a free joint, so that it can move swivel-like in all directions. This is most important, because through it is explained the fact that the vocal bands may be either tensed and lengthened or relaxed and shortened.

The muscles act on these movable cartilages, and nearly all the changes in the vocal bands are brought about through the alterations in position of the arytenoid cartilages, to which they are attached behind.

Before describing the muscles of the larynx, the reader is reminded of the order of structures from above downward, in front, which is as follows:

The hyoid bone.The thyro-hyoid membrane.The thyroid cartilage.The crico-thyroid membrane.The cricoid cartilage.The trachea.

The latter is connected with the cricoid cartilage by its membrane.

All the above structures can be felt in one's own person, the more readily if he be thin and have a long neck. The hyoid bone, or tongue-bone, is that hard structure just above the cricoid cartilage, and which one may easily demonstrate to be much more movable than the larynx itself. The tongue muscles are attached to it above, andfrom it, below, the larynx is suspended, as already explained.

The muscles of the larynx are best understood if the principle of antagonistic action already referred to be remembered. Speaking generally, the muscles are arrangedin pairswhich have an opposite or antagonistic action—viz.: (1) Those that open and close the glottis; (2) those that regulate the tension, or degree of tightness, of the vocal bands.

1. The muscles whose action tends to approximate the vocal bands—theadductors—are thearytenoidēus propriusand thethyro-arytenoidēus. The former is attached to the posterior or back surface of both arytenoid cartilages; the latter, as its name indicates, to the anterior and inner surface of the thyroid and the anterior lower surface or angle (vocal process) of the arytenoid.

Fig. 30

Fig. 30 (Chapman). Diagram showing action of crico-thyroid muscle, stretching of the vocal cords, and lengthening of them. The dotted lines indicate the position assumed when the muscle has contracted.

The opening or widening of the glottis is effected on each side (one muscle of the pair and its action being alone described in this and other cases) by the antagonist of these muscles, thecrico-arytenoidēus posticus, whose attachments are exactly as indicated by the names—viz., to the posterior part of the two cartilages named. When reading the description of these or other muscles it is absolutely necessary to have a pictorial illustration or the real object before one. The pull of this muscle is from the more fixed point, as in all other cases; hence the force is applied in a direction from below and outward, with the result thatthe arytenoid cartilage is tilted outward, and with it the vocal band is moved from the middle line.

Fig. 31

Fig. 31 (Spalteholz). View of the larynx as looked at from above. The illustration shows particularly well both the true and the false vocal bands. The true vocal bands are placed much as they are when a barytone is singing a very low tone. The part of the figure lowest on the page represents the back part of the larynx.

Fig. 32

Fig. 32 (Spalteholz). A cross-section transverse to the larynx, such as can be readily made with a strong knife.

Thecrico-thyroidalso tends to open the glottis. Just as the diaphragm is the most important muscle of breathing, so is the crico-thyroid the most important in ordinary speaking and in singing in the lower register. It is a relatively large and strong muscle with an oblique direction in the main, though it is composed in reality of several sets of fibres some of which are much more oblique in direction than others (Fig. 28). As its name indicates, its points of attachment are to the thyroid and the cricoid cartilages, but the most fixed point (origin) is its point of attachment to the larger cartilage; hence its direction of pull is from the thyroid, with the result that the anterior part of the cricoid is drawn up, the posterior part down, and the arytenoid cartilage, resting on the upper part of the cricoid, backward, so that the vocal band is rendered longer and more tense (see especiallyFig. 29). It is important to note that this is the muscle most used in singing the lower tones of the scale, and that its action must necessarily cease, to a great extent, when a certain point in the pitch is reached, as there is a limit to the degree of contraction of all muscles; and, besides, the crico-thyroid space is of very moderate size, and the cricoid cartilage can ascend only within the limits thus determined. It thus follows that Nature has provided in the change of mechanism for a new register, which is nothing else thana change of mechanism with a corresponding change of function. It will be at once apparent that the claim that registers are an invention of men, and without foundation in nature, is without support in anatomy and physiology. The crico-thyroid is probably, however, of much more importance to tragic actors and barytones than to tenors or sopranos. This, however, is no excuse for the neglect of its development by the latter class, as often happens, for without it the best tones of the lower register are impossible. On the other hand, the elocutionists who prescribe for students practices that involve the excessive use of this muscle, with a cramped position of the vocal organs, the larynx being greatly drawn down, with the view of producing disproportionately heavy lower tones, must take no comfort from the above anatomical and physiological facts. Art implies proportion, and it was one of the ambitions of all the best actors in the golden age of histrionic art to have an "even voice"—i.e., one equally good through the whole range required. The tragic actor, elocutionist, and public speaker, and the singer, whether soprano or bass, should neglect no muscle, though they may be justified in developing some in excess of others, but ever with a watchful eye on the weakest part.

2. The muscles which regulate the tension of the vocal bands are the following:

(a) Thethyro-arytenoidēus(pair), which by tilting the arytenoid cartilages forward relaxes thetension of the vocal bands. When they act with the adductors—e.g., the arytenoidēus proprius—the result must be relaxation and approximation behind, which implies a greater or less degree of shortening, as usually happens when a certain point in an ascending scale is reached in persons whose methods of voice-production have not been in some way modified, and a new register begins, which in most female voices is marked by a more or less distinct and abrupt alteration of the quality of the tone.

The crico-thyroids are the antagonists of the above-named muscles, and they may act either very much alone or, to some extent, in coöperation with the above, to regulate or steady their action; for in movements so complicated as those required for voice-production it is highly probable that we are inclined to reduce our explanations of muscular action to a simplicity that is excessive, and to appreciate but inadequately the delicacy and complexity of the mechanism and the processes involved. It is quite certain that in the production of the highest tones of a tenor or soprano several muscles coöperate, and one, especially, seems to be of great importance in the formation of such tones, most of all, perhaps, in high sopranos. The muscle referred to is the thyro-arytenoid already described. It is not only attached to the two cartilages indicated by its name, but also along the whole of the external or outer surface of the vocal band. It will be remembered that practically allthe muscles are arranged in pairs, one on each side of the middle line. The muscle now under consideration, more, perhaps, than any other, is complex in its action. Apparently a very few of its fibres may act more or less independently of all the others at a particular moment and with a specific and very delicate result, a very slight change in pitch. Exactly how this is attained no one has as yet adequately explained; but it is doubtful whether any singer who does not possess a perfect control over this muscle can produce the highest tones of the soprano with ease and effectiveness. It is especially the muscle of the human birds of the higher flights.

(b) To these thyro-arytenoids, which for most singers and all speakers are probably chiefly relaxing in action, must be added as aiding in this function another pair, thelateral crico-arytenoids. They are situated between the cricoid and arytenoid cartilages, and the direction of action is obliquely from below and forward, upward, and backward, so that the arytenoids are brought forward and also approximated more or less, which involves relaxed tension, at least, possibly also shortening of the vocal bands.

Fig. 33

Fig. 33 (Spalteholz). Shows various structures, and especially well the false and the true vocal bands, with the space between them (ventricle of Morgagni), but which has no special function in phonation, unless it acts as a small resonance-chamber, which is possible. This space is a natural result of the existence of two pairs of vocal bands in such close proximity.

When a tenor or soprano singer reaches the upper tones, say aboute'' f'' g'', or higher, there is considerable closing up in the larynx, much in the way in which the parts of the month are brought together in sucking. This is termedsphincter action, the mouth and the eyesbeing closed by such action, of which they are the most easily observed examples. As a result of this squeezing there is in some cases that reddening of the face and that tightness which is often felt uncomfortably, and which isstraining, because when present in more than a very slight degree it is injurious, owing to congestion or accumulation of blood in the blood-vessels, with all the bad consequences of such a state of things. When the tightening does not go beyond a certain point it is normal—indeed, such sphincter action is inevitable; but it is the excess which is so common in tenors and others who strain for undue power, and to produce tones too high in pitch for their development or their method, which is so disastrous to the throat and to the best art also.

Fig. 34

Fig. 34 (Spalteholz). Parts have been cut away to expose to view the whole of the inner surface of the larynx (lined with mucous membrane). An excellent view of the vocal bands and of the "ventricle" of the larynx, between them, is afforded.

When the vocal bands are in action their vibrations are accompanied by corresponding vibrations of the cartilages of the larynx—a fact of which any one may convince himself by laying his fingers on the upper part of the thyroid, especially when a low and powerful tone is produced. This vibration is not confined to the larynx, but extends to other parts—e.g., the chest itself, for when one speaks or sings a distinct vibration of the chest walls can be felt, though the extent to which this is present is very variable in different persons. As an ascending scale is sung the larynx can be felt (by the fingers) to rise, and the reverse as the pitch is lowered. This is due partly to the action of those muscles attached to the larynxwhich are not connected with the movements of the vocal bands, and partly to the influence of the expiratory air-blast. The glottis, partially closed as it must be in phonation, presents considerable resistance to the outgoing stream of air, hence the upward movement of the larynx when it is left free, and not held down by muscular action.

In singing and speaking the larynx should be steadied, otherwise the "attack," or application of the air-blast to the vocal bands, cannot be perfect. On the other hand, it is obviously incorrect to attempt to hold the larynx always in the same position. Holding down this organ by main force, as in the production of the so-called "straw bass," is one of the surest methods of producing congestion and consequent disorders of the vocal organs; and the author wishes to warn all voice-producers against such unnatural practices. Students of elocution and young actors often sin in a similar way, and "clergyman's sore throat" is almost always due to this or some similar misuse of the vocal organs. One's own sensations and common sense should never be disregarded, however eminent the teacher who recommends unphysiological methods.

When the student has read the above description of the structure and functions of the larynx, and studied the illustrations well, he will be prepared to deal with the subject in a practical manner, and without that it is feared his ideas will remain somewhat hazy.

First of all, he should try to find the parts mentioned in his own person, following this up by examinations of others, for which purpose children make good subjects, as they have usually necks that are not too deeply padded with fat, and they may be easily led to take the examinations as a sort of fun.

From above downward one feels in the middle line the parts in the order previously mentioned, beginning with the hyoid bone. One may learn that the larynx is movable and yielding, a hard structure covered with softer tissues, but what these are, and much more, can only be learned by examination of the larynx after it has been removed from some animal. Every butcher can provide the material for getting a sound, practical knowledge of the respiratory apparatus. He may be asked to supply the following:

1. A pig's "pluck"—i.e., the "lights," or lungs, with the windpipe attached. The liver, heart, etc., are not required, though to observe the relations of the circulatory system—i.e., the heart and large blood-vessels—to the respiratory system will be time well spent. Unless special instructions are given, the larynx, which the butcher may term the "weezend," may be lacking or mutilated. It should be explained that this organ, with a part of the windpipe and the extreme back part of the tongue, and all below it, are required. For onesitting this single "pluck" will suffice, as it will serve for a general examination. The lungs may be dilated by inserting a tube into the windpipe, tying it in position, and blowing into it with greater or less force. It should be especially observed how suddenly the lungs collapse when the breath force is removed, as this illustrates well theirelasticity. By cutting through the windpipe lengthwise and following it downward one learns how numerous are the branches of the bronchial tree, etc.

For a second sitting one should secure at least two specimens of the larynx of the pig or sheep, though the former is more like the human, and so the better on the whole. A case of dissecting instruments is not essential; a sharp pocket-knife will serve the purpose. In order that the student may have a clear idea of the cartilages, all the soft tissues must be cut or scraped away. It is necessary to exercise great care, or the membranes connecting the cartilages together will be cut through; and on the other hand, unless the work in the neighborhood of the arytenoids be cautiously done, these cartilages may be injured, and it is most important that their swivel-like action and their relations to the true vocal bands be observed. The glottic chink can be seen from above or below, and should be observed from both view-points. Its margins are formed by the true vocal bands.

Then, with the figures before him, the student should endeavor to isolate each of the muscles described. The muscles can always be recognized by their red color, but it is to be remembered that those on the inner surface of the larynx, such as the crico-arytenoid, are covered with mucous membrane, which after death is very pale. This can by careful dissection be removed, and if in doing this a small pair of forceps be employed, the work will be greatly facilitated. One must be very skilful indeed if he would get all the muscles "out," or well exposed to view as individuals, on a single specimen. Likely several will be required before entirely satisfactory results are reached, but these are well worth all the time and labor required. The action of the muscles can in some measure be demonstrated by pulling on them in the direction of their loosest attachment, though it must be confessed this is much more difficult in the case of most of the muscles of the larynx than in those of other parts of the body.

Should the specimens be very successfully dissected, it may be worth while to keep them for future observation, in rather weak alcohol (40 per cent.), in, say, a preserve jar.

All examinations of the vocal bands may leave the observer disappointed; he may fail to realize, most likely, how such wonderful results can be accomplished by structures so simple as those he sees before him. But when the laryngoscope is brought into use, then comes a revelation. This instrument will be described in the next chapter.

Some of the hygienic principles involved have already been referred to and illustrated, and others follow from the facts already set forth. It is very important for the voice-user to bear in mind that his larynx is a part of the respiratory tract, and that the whole of this region and the entire digestive tract, part of which is common to both, are lined with mucous membrane. If the nose be affected with catarrh, the throat does not usually long escape; and if the back of the mouth cavity (pharynx) be disordered, the vocal bands and other parts of the larynx are almost sure to be involved more or less.

The condition of the stomach is reflexly, if not by direct continuity through the mucous membrane, expressed in the throat generally; hence as experience shows, the voice-user cannot exercise too great care as to what and how much he eats, especially before a public appearance. He must know himself what best suits him, in this regard, to a degree that is necessary for few others.

When singing, more blood is sent to the organs used, hence the great danger of that excess of blood being retained in the parts too long, as might easily happen from pressure about the neck, etc. It is scarcely necessary to point out that draughts, cold rooms, etc., will also determine the blood from the skin inward, and set up that complicated condition of multiform evils known as "a cold."The obvious principle of prevention lies in keeping the body, and especially the neck, shoulders, and chest, warm after using the vocal organs in any way in public. To hand the singer a wrap after leaving the platform is always wise, and the judicious friend will see that conversation is not allowed, much less forced on the possibly breathless and wearied voice-user—a precaution that is probably more honored in the breach than in the observance, for in this as in other cases one's friends are sometimes his worst enemies.

The larynx is the most important organ in voice-production, and consists of cartilages, muscles, the vocal bands, true and false, membranes and ligaments, folds of mucous membrane, etc. It is situated between the hyoid (tongue) bone above and the trachea below. The cartilages are the (1) epiglottis, (2) thyroid, cricoid, arytenoid, the two small, unimportant cornicula laryngis, or cartilages of Santorini, surmounting the arytenoids, and the two cuneiform, or cartilages of Wrisberg, in the folds of mucous membrane on each side of the arytenoids.

The muscles are attached to the main cartilages. In addition to the muscles that are concerned with the movements of the vocal bands, others that hold the larynx in place or raise and lower it are attachedexternallyto these, especially to the large thyroid cartilage. The epiglottis, the false vocalcords, the true vocal cords, and the thyro-arytenoid muscles are attached to the interior anterior surface of the thyroid in this order from above down.

The false vocal bands have no direct function in phonation.The whole larynx, so far as phonation is concerned, may be said to exist for the true vocal bands.They are attached close together to the internal and anterior surface of the thyroid in front and to the lower anterior angles (vocal processes) of the arytenoids behind. Between the false vocal bands above and the true vocal bands below there is a cavity (the ventricle of Morgagni). The false vocal bands are protective, and approximate closely during coughing, swallowing, etc.

It is very important to note that the arytenoid cartilages move freely on their base, swivel-like, so that nearly all the changes effected in the movements and tension of the vocal bands are brought about through alterations in the position of these cartilages; and this implies that all the muscles concerned are attached to them. From above down, in front, the order of structures is as follows:

Hyoid bone.Membrane.Thyroid cartilage.Membrane.Cricoid cartilage.Trachea.

The hyoid bone is not a part of the larynx, but from it the larynx is suspended. The bone itself gives attachment to the muscles of the tongue. The glottis is the chink between the true vocal bands.

The muscles of the larynx may be divided into the following: (1) Those that open and those that close the glottis; (2) those which regulate the tension of the vocal bands. The latter include the (a) crico-thyroids, which tense and elongate them, (b) thyro-arytenoids, which relax and shorten them. The crico-thyroid may be considered the most important muscle of phonation, because it is so much used and so effective. By its action the cricoid is pulled up in front and down behind, so that the arytenoids are drawn back, and thus the vocal bands tensed and lengthened. The lateral crico-arytenoids and the thyro-arytenoids have the opposite effect—i.e., they relax and shorten the vocal bands; hence when they come into play a new register begins. The thyro-arytenoids, attached along the whole length of the vocal bands externally, have a very important but not well-understood action in the production of the higher tones, and probably also of the falsetto.

The whole larynx is lined with mucous membrane, that covering the true vocal bands being very thin. The false vocal bands are made up chiefly of mucous membrane; the true vocal bands abound in elastic tissue. The larynx rises during the production of high tones, and during phonation its vibrations may be felt, as also those of the chest.

Practical.

1. Feel in your own person the parts of the larynx, etc., from above down.

2. Note the vibration of the larynx when a vowel is spoken or sung. A similar vibration of the chest walls may be felt by the hands laid over them.

3. Note the change of position of the larynx in singing a scale.

4. Dissect a pig's or sheep's pluck and some specimens of the larynx.

Fig. 35

Fig. 35. These three figures illustrate perhaps more clearly theactionof the muscles indicatedFigs.26-34.The arrows show the direction of the pull of the muscles. The result of this action is the new position of the cartilages and vocal bands, which is shown by red outlines. The muscle is also depicted in red. The heavier outer rim is to indicate the thyroid cartilage. By comparing the upper and the lowest figure it will be seen that they are opposites. Of course, in phonation the vocal bands are never so much separated as shown in the illustrations. Rather does the lower figure indicate a case of extreme separation due to a very deep inspiration. However, these illustrations are merely diagrams meant to indicate in a general way the manner of the working of parts. For exact pictures of the vocal bands and related parts, seeChapter VII.

Fig. 35. These three figures illustrate perhaps more clearly theactionof the muscles indicatedFigs.26-34.

The arrows show the direction of the pull of the muscles. The result of this action is the new position of the cartilages and vocal bands, which is shown by red outlines. The muscle is also depicted in red. The heavier outer rim is to indicate the thyroid cartilage. By comparing the upper and the lowest figure it will be seen that they are opposites. Of course, in phonation the vocal bands are never so much separated as shown in the illustrations. Rather does the lower figure indicate a case of extreme separation due to a very deep inspiration. However, these illustrations are merely diagrams meant to indicate in a general way the manner of the working of parts. For exact pictures of the vocal bands and related parts, seeChapter VII.

Beforediscussing our subject further it is desirable that some attention be given to a few of the fundamental principles of that department of physics termedacoustics, and which deals with the subject of sound. If the student has the opportunity to study this subject theoretically and practically, as it is set forth in some good work on physics, he will have no reason to regret the time spent. A deep knowledge of the laws of sound is not absolutely essential, or even highly necessary, for a sufficient understanding of the principles involved in voice-production. It is, however, all-important that a few facts and principles be thoroughly grasped.

For those who feel that they have the time for a study of acoustics, the author would especially recommend Tyndall's work on sound, in which the subject is treated with wonderful clearness and charm. What we endeavor now to bring before the reader we have found sufficient for nearly all the purposes of the voice-user.

An observer on the street, looking at a military band, notices certain movements of one member of the organization which result in what he termed the sound of the drum; but a deaf man by his side,though he sees the movements, hears nothing. This, being analyzed, means that the movements of the drummer's arm, conveyed through the drumstick to the membrane of the drum, give rise to movements in it which set up corresponding movements of the air within the drum, which again cause movements of the body of the instrument, the whole causing movements of the external air; and here the purely physical process ends. The movements other than muscular ones are not readily observed, but experiments not only prove that they exist, but demonstrate their nature, even to their exact rate of occurrence, their size, etc. These movements are termedvibrations, and, as has been indicated previously, they are the sole physical cause of sound. But that the latter is not due wholly to a physical origin is evident from the fact that sound for the deaf does not exist. It must, therefore, be a personal, a subjective experience, and as the sleeping, unconscious person does not necessarily hear a sound, the process is not wholly a corporeal or physiological process; it is finally an experience of the mind, the consciousness, and so is psychological as well as physiological.

The fact that sound has a physical basis in the vibrations of bodies, either solid, liquid, or gaseous, may be brought home to one in various ways. Concussion or shaking of some kind is essential to start these vibrations. The air is made up of its particles, and one being movedsets up, inevitably, movements in neighboring particles on all sides, hence vibrations travel in all directions; which explains why a sound in the street may be heard by those in every part of the street not too distant, and also in the upper rooms of the houses and below in the basements. This is an important fact for the singer or speaker to bear in mind. His purpose must be to set up vibrations that will travel with great perfection and rapidity in all directions.

The following experiments of a simple kind will serve to convince those who may not have given much attention to the subject that sound is due to movements of some object, which we term the sounding body, strictly that which starts the vibrations by its own movements or vibrations.

If a sufficiently flexible band of metal or a stiff piece of whalebone be fixed at one end in a vice, and then sharply pulled to one side and suddenly let go, a sound results. The same effect is produced when a tight cord or small rope is plucked at and then suddenly released. In each of these cases, if actual movements are not seen, a certain haze which seems to surround the object may be observed. The same can be seen when a tuning-fork is set into action by a bow, a blow, etc. In the case of the fork a graphic tracing (Fig. 36) can be readily taken on smoked paper, thus demonstrating to the eye that vibrations exist, that they occur with perfect regularity and with a frequency that can be measured.

Fig. 36

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