MECHANISM OF THE PRODUCTION OF THE VOICE. 555 



tions of the diaphragm and the abdominal muscles. From the fact that the diaphragm, 

 as an active inspiratory muscle, is exactly opposed to the muscles which have a tendency 

 to push the abdominal organs, with the diaphragm over them, into the thoracic cavity, 

 and thus to diminish the pulmonary capacity, the expiratory and inspiratory acts may 

 be balanced so nicely that the most delicate vocal vibrations can be produced. The 

 glottis, thus closed as a preparation to a vocal act, presents a certain amount of resist- 

 ance to the egress of air. This is overcome by the action of the expiratory muscles, 

 and, with the passage of air through the chink, the edges of the opening, which are formed 

 by the true vocal chords, are thrown into vibration. Many of the different qualities 

 that are recognized in the human voice are due to differences in the length, breadth, and 

 thickness of the vibrating ribbons ; but, aside from what is technically known as quality, 

 the pitch is dependent chiefly upon the length of the opening through which the air is 

 made to pass and the degree of tension of the chords. The mechanism of these changes 

 in the pitch of vocal sounds is well illustrated by Garcia in the following passage, which 

 relates to what is known as the chest-voice : 



" If we emit veiled and feeble sounds, the larynx opens at the notes r^y ] H"iq, 

 and we see the glottis agitated by large and loose vibrations through- pE~ rt~ 

 out its entire extent. Its lips comprehended in their length the do> re> mL 



anterior apophyses of the arytenoid cartilages and the vocal chords ; but, I repeat it, 

 there remains no triangular space. 



" As the sounds ascend, the apophyses, which are slightly rounded on their internal 

 side, by a gradual apposition commencing at the back, encroach on the length of the glottis ; 



and as soon as we reach the sounds r~&~ [ they finish by touching each other 



throughout their whole extent ; pfe" 11 | I | but their summits are only solidly 

 fixed one against the other at i) -&--+- the notes [ J} izuj. In some 



organs these summits are a little va- <, do. cillating -((T) 1- J when they 



form the posterior end of the glottis, and two or three half-tones tJ i* 1 which are 



formed show a certain want of purity and strength, which is do, re. very well 



known to singers. From ri$:~ ^qthe vibrations, having become rounder and 



purer, are accomplished by p^ pzz|EE| the vocal ligaments alone, up to the end of 



the register. ^T~|J- ** 



" The glottis at this do, re. moment presents the aspect of a line swelled 



toward its middle, the length of which diminishes still more as the voice ascends. We 

 shall also see that the cavity of the larynx has become very small, and that the superior 

 ligaments have contracted the extent of the ellipse to less than one-half." 



These observations have been in the main confirmed by Battaille, Emma Seiler, and 

 all who have applied the laryngoscope to the study of the voice in singing. On several 

 occasions we have had opportunities of observing, by means of the laryngoscope, the 

 changes in the form of the glottis during the production of vocal sounds of different de- 

 grees of pitch ; and the various points to which we have alluded can be illustrated by 

 autolaryngoscopy in the most marked manner. Nothing can be more striking than the 

 changes thus observed in the form of the glottis in a transition from low to high notes. 

 We have also frequently noted the general appearance of the glottis in phonation in ex- 

 periments upon animals in which the glottis has been exposed to view, although the 

 phenomena are much less striking than they are in the human subject. 



Variations in the Quality of the Voice, depending upon Differences in the Size and 

 Form of the Larynx and the Vocal Chords. We are all sufficiently familiar with the char- 

 acters of the male as distinguished from the female voice, and with what are known as the 

 different vocal registers. In childhood, the general characters of the voice are essentially 

 the same in both sexes. The larynx is smaller than in the adult, and the vocal muscles 

 are evidently more feeble ; but the quality of the vocal sounds at this period of life is 

 peculiarly pure and penetrating. While there are certain characters that distinguish the 

 voices of boys before the age of puberty, they present, as in the female, the different qualities 



