XXXII. THE VOICE. 



In the study of the ear we noted that sounds are pro- 

 duced by setting in vibration various objects, which 

 vibrations are propagated as waves of air. When the 

 air waves reach the ears they produce impulses of sound. 

 In our study of the respiratory system we noted that in 

 the human body the expired air was capable of producing , 

 sounds and that the various modifications of these sounds 

 were called the voice. Combining these two observa- 

 tions we should expect to find in our bodies some struc- 

 ture in which vibrations of different pitch, loudness, and 



Fig. 227 — The larynx; A, front view; J3, side -view; C, back view. 



quality could be set up by expired air. Such an instru- 

 ment, in fact, is found in the, larynx or cartilage box at the 



486 ' 



