VOCAL CORDS AND THE EARS 301 



when air is forced out between them. Because of this 

 difference between the vocal cords of men and women, 

 men cannot sing such high notes as women, and women 

 cannot make the low tones of the bass. A man's voice 

 is about one octave lower than a woman's voice. The 

 voice of a boy has the same pitch as that of a girl. A boy's 

 voice drops one octave between the ages of 14 and 18 years. 

 The difference between a soprano and an alto voice is 

 merely one of length, tension, and thickness of the vocal 

 cords. The difference between a tenor and a bass voice 

 is caused by the same variations. 



The loudness of the voice depends upon the force with 

 which the cords vibrate, and this depends upon the force 

 with which the air is expelled from the lungs when passing 

 between the cords. While whispering the vocal cords are 

 so far apart that the small amount of air passing through 

 does not make them vibrate, but the current of air is 

 checked at intervals and modified by the organs of speech. 



207. The Voice. The quality of the human voice is 

 determined principally by the condition of the chest, 

 windpipe, mouth, and nose. The air in these organs is 

 caused to vibrate by the vocal cords. The nasal twang 

 is produced when the nasal passages are partly or com- 

 pletely closed by a cold or by a growth of tissue called 

 adenoids. Hoarseness is due to a swelling of the cords, 

 resulting from the blood and lymph (a colorless liquid) 

 collecting in them because of a cold or too-long-continued 

 use. To train the voice, then, is to remove all these 

 needless obstructions, to learn how to control the action 

 of the cords and make them respond at will, and to de- 

 velop the resonant parts so that the qualities of beauty 

 and clearness will be gained. It is important that every- 

 one should cultivate a smooth and pleasant tone of voice. 



