HELMHOLTZ IN BONN 



the mouth is then blown like an organ pipe, and by 

 its resonance reinforces the corresponding partials in 

 the rushing wind-like noise. Helmholtz adopted 

 another method. To determine the pitch of the 

 cavity of the mouth, considered as a resonance cavity, 

 he struck tuning-forks of different pitches, and held 

 them before the opening of his mouth. Then, the 

 louder the proper tone of the fork was heard the 

 nearer l it corresponded with one of the proper tones 

 of the included mass of air.' As the shape of the 

 mouth could be altered at pleasure, according to the 

 vowel to be emitted, it was easy to discover the pitch 

 of the included mass of air for each vowel. He came 

 to the conclusion that 'the pitch of the strongest 

 resonance of the oral cavity depends solely upon the 

 vowel for pronouncing which the mouth has been 

 arranged.' He also found the same resonances for 

 men as for women and children. He then carefully 

 examined the form of the oral cavity for each vowel, 

 and showed how very slight changes could account 

 for the quality being slightly altered for different 

 dialects. He also demonstrated that the tones of 

 the human voice are adapted to the powers of the 

 human ear. The ear, by its resonating powers, 

 favours the development of these partials, especially 

 the higher ones, which give a peculiar character to 

 human tones. His theory as to vowel-tone is summed 

 up in the following sentence : * Vowel qualities of 

 tone consequently are essentially distinguished from 

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