CHAPTER XXIX 



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SPEAKING AND HEARING 



275. Speech. The human voice is the most perfect of musi- 

 cal instruments. Within the throat, two elastic bands are at- 

 tached to the windpipe at the place commonly called Adam's 

 apple ; these flexible bands have received the name of vocal 

 cords, since by their vibration all speech is produced. In 

 ordinary breathing, the cords are loose and are separated by 



a wide opening through which air 

 enters and leaves the lungs. When 

 we wish to speak, muscular effort 

 stretches the cords, draws them closer 

 together, and reduces the opening 

 between them to a narrow slit, as in 

 the case of the organ pipe. If air 

 FIG. 193. The vibration of the from the lungs is sent through the 

 ^ C ha P n r C e e . StheS Und "arrow slit, the vocal cords or bands 

 are thrown into rapid vibration and 



produce sound. The pitch of the sound depends upon the 

 tension of the stretched membranes, and since this can be 

 altered by muscular action, the voice can be modulated at 

 will. In times of excitement, when the muscles of the body 

 in general are in a state of great tension, the pitch is likely to 

 be uncommonly high. 



Women's voices are higher than men's because the vocal 

 cords are shorter and finer ; even though muscular tension is 

 relaxed and the cords are made looser, the pitch of a woman's 

 voice does not fall so low as that of a man's voice since his 



300 



