2i 4 HUMAN PHYSIOLOGY CHAP. 



The vocal cords are stretched across the opening in 

 the larynx, being fastened behind, in front, and at the 

 sides to some of the cartilages. The cords are two thin 

 white bands of elastic tissue formed by folding the 

 mucous membrane which lines the larynx. 



Get a sheep's larynx from your butcher and notice the three 

 large cartilages, the vocal cords, the lining membrane, and the 

 muscles and connective tissue that hold the parts in place. 



When air is inhaled the vocal cords move apart 

 because some of the muscles of the larynx contract. 

 During exhalation they move slightly together again. 

 In producing voice the vocal cords are brought close 

 together and made tense by the action of small muscles 

 that move some of the cartilages. If air is forced out 

 of the lungs when the cords are in this position, they are 

 made to vibrate and give forth a sound. 



If you place your hand on the throat and sing the 

 scale, you will feel the larynx as a whole move slightly 

 up for the higher notes and down for the lower. For 

 the higher tones the cords are made more tense than for 

 the lower. The pitch of the tones depends upon the tension 

 of the cords and position of the larynx. The londness 

 depends upon tJie force with which air is expelled from 

 the lungs or the distance over wJiich the cords are made 

 to vibrate. 



151. Voice Sounds. Sounds produced by the vocal 

 cords may differ in pitch and loudness. But another 

 very important characteristic of the human voice is its 

 sweetness or quality. This depends chiefly upon the 

 large resounding chamber of the pharynx, nose, and 



