HERMANN VON HELMHOLTZ 



may be, produce that feeling of less and less con- 

 sonance until we come to intervals that are truly 

 dissonant. One might suppose that in the case of 

 tones that abound in partials, combinational tones 

 might be produced by the partials, and thus a new source 

 of beats might lead to confusion and discord ; but 

 theory shows that dissonance due to combinational 

 tones, produced between partials, never occurs except 

 when it has already taken place by the action of the 

 partials among themselves. 1 



Closely connected with this subject is the investiga- 

 tion of the cause of the quality of the human voice, 

 more especially as to vowel tones. This also engaged 

 the attention of Helmholtz, and it was treated by 

 him in his usual masterly fashion. 2 Why should a 

 vowel, spoken or sung, always have, even with the 

 voices of different persons, the same quality, so that 

 we have no difficulty in distinguishing A from E and 

 E from O ? Donders 3 was the first to show that the 

 cavity of the mouth, as arranged for the giving forth 

 of a vowel, was tuned as a resonator for a tone of 

 a certain pitch, and that different pitches corresponded 

 to the forms of the cavity for the different vowels. 

 This he discovered, not by the use of tuning-forks, 

 but by the peculiar noise produced in the mouth when 

 the different vowels are whispered. The cavity of 



1 Sedley Taylor, Sound and Music. London, 1873. 

 3 Gel. An%. d. k. bayer Acad. d. Wiaentch, 1859. 

 3 De Phytlologie der Spraak klanken, 1870, s. 9. 

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