404 



ferior ligaments, at the bottom of the larynx, form exclusively the 

 voice, whatever may be its register or its intensity ; for they alone 

 vibrate at the bottom of the larynx*. But by virtue of what prin- 

 ciple is the voice formed ? It seems to me, that the answer to this 

 question can be but this ; the voice is formed in one unique manner, 

 by the compressions and expansions of the air, or the successive and 

 regular explosions which it produces in passing through the glottis. 



The ligaments of the glottis are situate about the mean level of 

 the upper border of the cricoid, close the passage, and present a 

 resistance to the air. As soon as the air has accumulated suffi- 

 ciently, it parts these folds and produces an explosion. But at the 

 same instant, by virtue of their elasticity, and the pressure from be- 

 low being relieved, they meet again to give rise to a fresh explosion. 

 A series of these compressions and expansions, or of explosions, 

 occasioned by the expansive force of the air and the reaction of the 

 glottis, produces the voice. 



This theory, though now generally admitted for reeds, and un- 

 doubtedly evident in the liquid vein, the toothed-wheel of Savart, 

 the syrene of the Baron Cagnard Latour &c., has not to my know- 

 ledge, been yet applied to the glottis f. If we consider that the 

 lips of this aperture, taken separately, can. give no kind of sound, 

 however we may try to make them speak, we must admit that the 

 sounds which they give forth by their mutual action, are only owing 

 to the explosions of the air produced by their strokes}. It is not 

 necessary in order to obtain the explosion of sound, that the glottis 

 should be perfectly closed each time after its opening ; it suffices 

 that it should oppose an obstacle to the air capable of developing its 

 elasticity. In this case the rushing of the air is heard accompanying 



* We gladly acknowledge that this most important fact has been already 

 announced by J. Miiller, although we have our objections to the theory which 

 accompanies it. Handbuch der Physiologic des Menschen. 



t I find that Dr. Miiller hints at the possibility of the voice being thus formed, 

 but only to attack and reject the notion. Ibidem. 



} Many controversies have arisen respecting the sounds sometimes emitted by 

 animals after the section of the superior and recurrent laryngeal nerves ; sounds 

 which have been perhaps occasioned by the struggling of the animal causing a 

 swelling of the neck and a mechanical contact of the vocal ligaments. However, 

 without doubt, after the section of these nerves, voice, as a voluntary act, can no 

 longer take place. 



