432 



VOICE. 



[CHAP. XXXT. 



the voice. If a current of air be made to play on the vocal chords 

 by a bellows fixed to the tracheal end of the larynx, or by blowing 

 air through it, distinct vocal sounds are excited which can be 

 varied by altering the tension of the vocal chords. 



There is no instance of true voice among tlie lower orders of creation except 

 in those animals that have a larynx connected with the respiratory apparatus 

 as in man. In other words, all animals that have no larynx are voiceless. 

 The hum of insects is a phenomenon essentially different from voice, and is 

 caused by the rapid vibration of an apparatus connected with their wings. 

 All the other invertebrated classes are incapable of producing sounds. Fishes, 

 likewise are voiceless. The Batrachian reptiles possess a larynx, and can 

 Fig. 210. produce vocal sounds. The hiss- 



ing of serpents is, likewise, la- 

 ryngeal. But the Chelonian rep- 

 tiles have no voice. In birds 

 there are two organs placed, 

 the one in front of the other, to 

 which the name of larynx has 

 been given by anatomists; of 

 these, the lower, or that nearest 

 the lungs, is the true vocal ap- 

 paratus ; the upper is merely a 

 resonating or reciprocating ca- 

 vity destined to enhance the in- 

 tensity of the sounds generated 

 in the lower. Cuvier showed 

 that an opening between the two 

 organs did not destroy the power 

 of producing sounds, so long as 

 the inferior larynx was unin- 

 jured. 



The human larynx is a 

 kind of box, composed of 

 pieces which may be moved 

 on each other, and encloses 

 the membranous bands in 

 which the vocal vibrations 

 are produced. These pieces, 

 when articulated together, 

 constitute the skeleton of 

 the larynx. They are com- 



Cartilages of larynx and epiglotts, and upper rings of pOSed of Cartilage, and form 

 trachea m situ seen from behind. From a preparation in TT ~,, TT rt,,,^ 



the Anatomical Museum, King's College, by Mr. Cane. a VCry CUriOUS 



a. Arytenoid cartilages, b. Superior cornu. c. Inferior mi. prp QVA fi 



cornu. d. Posterior surface of cricoid. e. Foramen for supe- mere are U 



rior laryngeal nerve. /. Perforations of epiglottis, i. Upper /j. rt rf TirVir>li 



margin of thyroid, t. Trachea, h. Right inferior tubercle. {.tWO OI WniCJl 





