280 



Life and Health 



larynx be relaxed, the opening of the glottis is wider. Thus 



the air enters and leaves the larynx during breathing, with- 

 out throwing the cords into vibration 

 enough to produce any sound. 



In a general way, we may say that 

 the production of the voice is effected 

 by an arrangement like that of some 

 musical instruments, the sounds pro- 

 d.uced by the vibrations of the vocal 

 cords being modified by the tubes 

 above and below. 



All musical sounds are due to move- 

 ments or vibrations occurring with a 

 certain regularity, and they differ in 

 loudness, pitch, and quality. 



Loudness of the sound depends 

 upon the extent of the vibrations, and 

 pitch on the rapidity of the vibrations. 

 The quality depends upon the admix- 

 ture of tones produced by vibrations 

 of varying rates of rapidity, related to 

 one another. 



X437. Factors in the Production of 

 the Voice. We have just learned that 

 the pitch of sound depends on the 

 rapidity of the vibrations. This 

 depends upon the length of the cords 

 and .their tightness, for the shorter 

 and tighter a string is, the higher is 

 the note which its vibration produces. 

 The vocal cords of women are about 



one-third shorter than those of men, hence the higher 



pitch of the notes they produce. 



FIG. 152. Longitudinal 

 Section of the Larynx. 

 (Showing the vocal 

 cords.) 



A, epiglottis ; B, section of 

 hyoid bone; C, superior 

 vocal cord; D, ventricle 

 of the larynx ; E, inferior 

 vocal cord ; P, section of 

 the thyroid cartilage ; //, 

 section of anterior portion 

 of the cricoid cartilage; 

 K, trachea ; L, section of 

 the posterior portion of 

 the cricoid cartilage ; M, 

 arytenoid cartilage ; A^, 

 section of the arytenoid 

 muscle. 



