THE VOICE. 



593 



What are the mechanisms by which voice is produced in 

 man ? Observation proves that the following are essential: 1. 



Fig. 489. 



Fig. 430. 



Fig. 429.— Longitudinal section of human larynx (after Sappey). 1, ventricle of lar- 

 ynx; 3, superior vocal cord; 3, inferior vocal cord; 4, arytenoid cartilage; 5, sec- 

 tion of arytenoid muscle; 6, 6, inferior portion of cavity of lai-ynx; 7, section of 

 SostCTior part of cricoid cartilage; 8, section of anterior part of same; 9, superior 

 order of cricoid cartilage; 10. section of thyroid cartilagej 11. II, superior portion 

 of cavity of larynx; 12, 18, arytenoid gland; 14, 16, epiglottis; 15,17, adipose tissue; 

 18, section of hyoid bone; 19, 19, 20, trachea. 



Fig. 430.— Posterior aspect of muscles of human larynx (after Sappey). 1, posterior 

 crico-arytenoid muscle; 3, 3, 4, different fasciculi of arytenoid muscle; 5, aryteno- 

 epiglottidean muscle. 



A certain amount of tension of the vocal cords (bands). 2. A 

 certain degree of approximation of their edges. 3. An expira- 

 tory blast of air. 



It will be noted that these are all conditions favorable to the 

 vibration of the vocal bands. The greater the tension the 

 higher the pitch ; and the more occluded the glottic orifice the 

 more effective the expiratory blast of air. 



The principle on which the vocal bands act may be illus- 



