THE VOICE 353 



638. Benefits of vocal exercise. -In singing and lec- 

 turing, the breathing must be regular and deep. The 

 abdominal muscles must act, and often a sound must be 

 prolonged until the air in the lungs is exhausted. The 

 respiratory muscles must act continuously and strongly 

 and for long periods of time. Thus an increased amount 

 of oxygen will be taken into the body. Voice training is 

 one of the best modes of exercise, especially for a weak 

 person who cannot endure long walks or gymnastic exer- 

 cises. It is all the more valuable because a person does 

 not think of the exercise, but directs the mind to an inter- 

 esting and useful occupation. 



639. Diseases of the larynx. In a cold in the throat 

 the mucous membrane becomes tender and swollen. Then 

 the movements of the vocal cords are impeded and painful, 

 so that only a hoarse sound, or no sound at all, can be 

 produced. By repeatedly overworking the vocal cords, 

 they and the muscles of the larynx become flabby and 

 tender so that their vibrations are painful or impossible. 

 Then the voice is reduced to a whisper. Sometimes the 

 nerves of the larynx are paralyzed so that no motor orders 

 can reach the muscles. Then no sound can be formed. 



640. In mouth breathing, the air is drawn directly into the larynx 

 without being purified, warmed, and moistened in the nose. This irri- 

 tates the larynx and vocal cords so that the voice is made weaker and 

 harsher. A mouth breather can seldom become a good singer or 

 speaker. 



641. Tobacco. Tobacco smoke may produce such an 

 irritation that there is a constant hacking cough. Cigar- 

 ettes are especially bad for the voice, for the smoke is 

 deeply inhaled. Alcohol interferes with the voice by 

 inducing indigestion and weakness of the muscles. 



ov. PHYSIOL. 23 



