THE PHONOGRAPH, OR VOICE-RECORDER. 281 



many respects differ widely from ordinary tones are repeated, 

 and the peculiariries of intonation which distinguish one 

 voice from another have been faithfully reproduced. 



Let us consider in what respects vocal sounds, and 

 especially the sounds employed in speech, differ from mere 

 combinations of ordinary tones. 



It has been said, and with some justice, that the organ 

 of voice is of the nature of a reed instrument. A reed 

 instrument, as most persons know, is one in which musical 

 sounds are produced by the action of a vibrating reed in 

 breaking up a current of air into a series of short puffs. 

 The harmonium, accordion, concertina, etc., are reed instru- 

 ments, the reed for each note being a fine strip of metal 

 vibrating in a slit The vocal organ of man is at the top of 

 the windpipe, along which a continuous current of air can be 

 forced by the lungs. Certain elastic bands are attached to the 

 head of the windpipe, almost closing the aperture. These vocal 

 chords are thrown into vibration by the current of air from 

 the lungs ; and as the rate of their vibration is made to vary 

 by varying their tension, the sound changes in tone. So far, 

 we have what corresponds to a reed instrument admitting of 

 being altered in pitch so as to emit different notes. The 

 mouth, however, affects the character of the sound uttered 

 from the throat. The character of a tone emitted by the 

 throat cannot be altered by any change in the configuration 

 of the mouth ; so that if a single tone were in reality pro- 

 duced by the vocal chords, the resonance of the mouth 

 would only strengthen that tone more or less according to 

 the figure given to the cavity of the mouth at the will of the 

 singer or speaker. But in reality, besides the fundamental 

 tone uttered by the vocal chords, a series of overtones are 

 produced. Overtones are tones corresponding to vibration 

 at twice, three times, four times, etc., the rate of the vibration 

 producing the fundamental tone. Now the cavity of the 

 mouth can be so modified in shape as to strengthen either 

 the fundamental tone or any one of these overtones. And 

 according as special tones are strengthened in this way 



