2i 8 HUMAN PHYSIOLOGY CHAP, xv 



7. The vocal cords are two thin folds of mucous membrane 

 stretched across the open space in the larynx. 



8. The cords move apart in inhalation, and together in ex- 

 halation. They may be stretched tight, and caused to vibrate 

 by the breath as it is forced out of the lungs. 



9. Difference in pitch depends upon differences in the 

 tension of the vocal cords and in the position ofthe larynx as 

 a whole. 



10. Loudness depends upon the force with which the breath 

 is expelled from the lungs, and the distance it makes the cords 

 move in their vibration. 



11. Quality depends upon the size and shape of the pharynx, 

 nasal cavities, and mouth. 



12. The lips, teeth, tongue, soft palate, and nose modify the 

 sounds made by the cords, and produce the various tones of 

 voice. 



13. The air passages should be unobstructed by adenoid 

 growths, enlarged tonsils, or polypi, and the respiratory muscles 

 unhampered by round shoulders, flat chest, curved spine, or 

 tight lacing. 



14. Voice culture, singing, and breathing exercises are im- 

 portant means of training the voice. The voice depends upon 

 the general health of the body. 



15. Much can be done to secure a strong, sweet, melodious 

 voice, and a pleasant, agreeable manner of speech. 



1 6. Tobacco, alcohol, hot foods or drinks, cause a conges- 

 tion and inflammation of the mucous membrane, and make the 

 voice harsh and disagreeable. 



