Voice production in singing and speaking, based on scientific principles

by Wesley Mills

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

The crico-thyroid also 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 especially [Fig. 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 than a 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) The thyro-arytenoidēus (pair), which by tilting the arytenoid cartilages forward relaxes the tension 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 all the 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, the lateral 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 (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.