1 2 1 8 ON VOCAL SO UNDS. 



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 would 

 account for the quality being slightly altered for different dialects. 



Helmholtz also showed that the tones of the human voice have a 

 peculiar relation to the human ear. Thus the upper partials of / are 

 in the neighbourhood of e"" up to g"" , and the human ear itself is tuned 

 to one of these pitches ; that is to say, by its resonance it favours the 

 perception of these tones. Powerful male voices produce these partials 

 strongly. Thus, a bass voice singing c produced the seventh partial d'"\ 

 eighth e"", ninth f"\ and the tenth g""\- Some of these partials, such 

 as e"" and f'"% may clash, and by producing dissonance, give harshness to 

 the voice. This illustration will show how Helmholtz, following out the 

 theory applicable to all musical instruments, endeavoured to explain 

 the quality of different voices. His theory as to vowel-tone is summed up 

 in the following sentence — " Vowel qualities of tone consequently are 

 essentially distinguished from the tones of most other musical instru- 

 ments, by the fact that the loudness of their partial tones does not depend 

 upon the numerical order, out upon the absolute pitch of those partials ; thus, 

 when I sing the vowel A to the note E\>, the reinforced tone o"\) is the 

 twelfth partial tone of the compound ; and when I sing the same vowel 

 A to the note V\>, the reinforced tone is still b"\>, but is now the second 

 partial of the compound tone sung." 1 



Further, Helmholtz endeavoured to demonstrate the correctness of 

 his view by synthetically combining the tones of certain tuning-forks in 

 his well-known vowel tone apparatus. 2 He, in early experiments, used 

 eight forks, the first being the fundamental tone si^, and the others the 

 first seven partials. Thus — 



siy\>, si 2 \>, fa. s , si a \>, re A , fa if Za 4 b, si 4 \>, 



The vowel is well sounded with this apparatus, when we sound si 3 \> 

 (characteristic of 0) strongly ; more feebly si,\>, fa 3 , re 3 , and the funda- 

 mental softly. OU is good with sijjo strong, and the partials feeble. 

 Using in another apparatus 



SI 



b, si s \>, fa v sij>, re b , fa b , la^>, si^y, 



OU was given with si.)y (the fundamental) alone. was sounded by 

 fundamental si 2 \y moderate, sijp strong, and /« 4 weak. If we sound si.Jp 

 (fundamental) along with si 3 \> and fa moderate, and s%\> and re h strongly, 

 we obtain A. This vowel is characterised by si 4 t>, along with the partials 

 si 3 \> and sip. To obtain U, give si 2 \> and sijp moderate, and/a 3 , la.Jp, and 

 si 3 \> as strong as possible. The characteristic partial of this vowel is 

 si 3 \>. We have performed many experiments with this apparatus, and 

 find the results obtained by Helmholtz to be consistent with our ex- 

 perience. Much depends, in the appreciation of this experiment, on 

 careful attention, practice, and a good ear. 



Konig investigated the subject with the aid of his manometric 



1 Helmholtz, "Sensations of Tone," p. 172. 



2 For figure and description of this famous apparatus, see M'Kendrick's " Physiology, 

 vol. ii. p. 691. 



