THE VOICE. 



It is convenient to speak, in the case of man, of the singing 

 voice and the speaking voice, though there is no fundamental 

 difference in their production. The voice of the lower animals 

 approximates the former rather than the latter. 



It is to be remembered that sound is an affection of the 

 nervous centers through the ear, as the result of aerial vibra- 

 tions. 



We are now to explain how such vibrations are caused by 

 the vocal mechanisms of animals and especially of man. 



The tones of a piano or violin are demonstrably due to the 

 vibrations of the strings ; of a clarionet to the vibration of its 

 reed. But, however musical tones may be produced, we distin- 

 guish in them differences in pitch, quantity, and quality. 



The pitch is dependent solely upon the number of vibrations 

 within a given time, as one second; the quantity or loudness 

 upon the amplitude of the vibrations, and the quality upon the 

 form of the vibrations. The first two scarcely require any fur- 

 ther notice ; but it is rather important for our purpose to under- 

 stand clearly the nature of quality or timbre, which is a more 

 complex matter. 



If a note be sounded near an open piano, it may be observed 

 that not only the string capable of giving out the correspond- 

 ing note passes into feeble vibration, but that several others 

 also respond. These latter produce the overtones or partials 

 which enter into notes and determine the quality by which one 

 instrument or one voice differs from another. In other words, 

 every tone is in reality compound, being composed of a fundar 

 mental tone and overtones. These vary in number and in relar 

 tive strength with each form of instrument and each voice; 

 and it is now customary to explain the differences in quality of 

 voices solely in this way; and this is, no doubt, correct in the 

 main. 



