A STUDY OF THE VOICE AND OF SPEECH 317 



apart by small muscles, and a V-shaped opening of consider- 

 able size is thus left between the vocal cords. Air then 

 passes inward or outward through the larynx without caus- 

 ing any sound. When, however, we wish to use the voice, 

 in singing or in speaking, the two arytenoids are pulled 

 close together by certain muscles of the larynx, and so only 

 a narrow space is left between the cords. Since the thyroid 

 can rock backward and for- 

 ward (by means of its lower 

 pegs) on the cricoid, other sets 

 of muscles pull the arytenoids 

 and, the thyroid apart from 

 each other, and by this means 

 the vocal cords are tightened. 

 We then force air outward 

 from our lungs, the membra- 

 nous cords are made to vibrate, 

 and a sound is produced. 



Resonating Cavities. If a 

 violin string is tightly 

 stretched across the corner FIG. 147. The 

 of a room and is then set in 

 motion, the resulting sound can 

 scarcely be heard. But when a 

 violin is played, the volume 

 of air inclosed by its thin 

 wooden walls is made to vi- 

 brate as well as the string, and 

 the loudiiess of the sound is 

 thus greatly increased. In a similar manner the sound of 

 our voice depends largely on the vibrating columns of air 

 in the throat, mouth, and nose. Certain bones of the skull 

 have hollow walls, too, which increase the sound produced 

 by our vocal organs. 



Speech. The words of which spoken languages are com- 

 posed consist of series of vowels and consonants. The 



Glottis, 

 from above. 



viewed 



Ary arytenoid cartilages. 

 Arp = muscles between 



arytenoids. 



Cal, Cap = muscles from ary- 

 tenoids to cricoid 

 cartilages. 



Cr = cricoid cartilages. 

 Th = thyroid cartilage. 

 V= vocal cords. 



