232 PRINCIPLES OF PHYSIOLOGY 



greater the amplitude, or extent of move- 

 ment, the louder the tone. This will be 

 largely determined, not so much by the force 

 of the current of air from the lungs as by 

 the degree of elasticity of the cords. 



139. The quality or timbre of the voice 

 depends on the same laws as determine the 

 quality of musical instruments. The tone 

 produced by the vibrations of the cords is a 

 compound tone depending on a fundamental 

 tone which gives the pitch, with which are 

 combined many partials or overtones, which, 

 as regards the number of their vibrations, are 

 simple multiples of the frequency of the 

 fundamental. Thus, if the fundamental tone 

 is produced by, say, 100 vibrations per 

 second, then the partials are in the order of 

 1, 2, 3, etc. ; that is, the first partial corresponds 

 to 200 vibrations per second, the second to 

 300, and so on. The cavities above the cords, 

 such as the space immediately above the 

 cords and below the so-called false cords, the 

 cavity of the pharynx, nasal passages, sinuses 

 in the bones of the face, and the mouth, all 

 act as resonance chambers. These develop, 



