DIFFERENCES IN THE PITCH OF THE VOICE 375 



Vocal cords. 



Our voice. A study of the figure will show us the lo- 

 cation of the vocal cords, which are instrumental in 

 producing sound. They are composed of two thin struc- 

 tures stretching from front to back across the voice box, 

 near the top of the lar- 

 ynx. They are attached 

 to the side walls. By 

 means of muscles the 

 tension of these cords 

 may be changed and the 

 size of the opening be- 

 tween the two outer 

 edges may be made larger or smaller. In deep breath- 

 ing, for example, they lie flat against the side walls of 

 the larynx, thus allowing a full entrance of air. But 

 when we make a sound they come very close together 

 so that only a narrow opening is made between them. 

 The tightly drawn cords are set into vibration by the 

 passing air, and sound results. 



Differences in the pitch of the voice. A child's voice 

 is shrill or high pitched. This is because the larynx is 



narrow and the vocal 

 cords are short. It 

 is a well-known fact 

 that long wires or 

 strings, when vibrat- 

 ing, give a much 

 lower and deeper 

 tone than do short strings. This is easily seen in picking 

 the mandolin or banjo. If you put your fingers on the frets, 

 making the string shorter, it gives a note of higher pitch. 

 When a boy's voice is breaking or changing, it means there 



The pitch of a string is raised by shortening the wire 

 and by increasing the tension on it. 



