492 MOVEMENTS VOICE AND SPEECH. 



into the lungs but entirely inactive in expiration, has now become a musi- 

 cal instrument, presenting a slit with borders capable of accurate vibra- 

 tions. 



The approximation of the posterior extremities of the vocal chords and 

 their tension by the action of certain of the intrinsic muscles are accom- 

 plished just before the vocal effort is actually 

 made. The glottis being thus prepared for the 

 emission of a particular sound, the expiratory 

 muscles force air through the larynx with the re- 

 quired power. The power of the voice is due 

 simply to the force of the expiratory act, which 

 is regulated chiefly by the antagonistic relations 

 of the diaphragm and the abdominal muscles. 

 From the fact that the diaphragm, as an inspira- 



FIG 169 Glottis seen with the t orv muscle, is exactly opposed to the muscles 



which have a tendency to push the abdominal 

 Bon )- organs, with the diaphragm over them, into the 



1, 2, base of the tongue ; 3, 4, epi- ,, . . , *, a ; ' TJJL 



glottis; 5, 6, pharynx ; 7. aryte- thoracic cavity and thus to diminish the pulmo- 



noid cartilages ; 8, opening be- ., xl . -, . 



tween the true vocal chords ; nary capacity, the expiratory and mspiratory acts 



9, aryteno-epiglottidean folds ; i i i " n -i ^ ^ , i V 



10, cartilage of Santorini ; ii, may be balanced so nicely that the most delicate 



cuneiform cartilage ; 12, supe- i -i , i -, -, rrn n j.^.- 



rior vocal chords ; 13, inferior vocal vibrations can be produced, ihe glottis, 

 thus closed as a preparation to a vocal act, pre- 

 sents a certain resistance 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 bands ; but aside from what is technically known as quality, 

 the pitch is dependent 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 illustrated by Garcia in the fol- 

 lowing, which relates to what is known as the chest-voice : 



"If we emit veiled and feeble sounds, the larynx opens at the notes 

 i3 anc ^ we see tn e glottis agitated by large and loose vibra- 



' ' tions throughout its entire extent. Its lips comprehended 



in their length the 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 rQ i 

 they finish by touching each other throughout their whole j^n- p^~1 | 

 extent ; but their summits are only solidly fixed one against *J pr'? 

 the other at the notes . Q . In some organs these summits are a 



little vacillating when [^__p~ | _[ they form the posterior end of the glot- 

 tis, and two or three cJ S^- ^ half-tones which are formed show a cer- 

 tain want of purity and strength, which is very well known to singers. From 



