452 VOICE AND SPEECH 



been ascertained experimentally that the overtones in each instance are 

 different as they are reenforced by the vibrations of air in the accessory 

 vocal organs, in some instances the third, in others, the fifth etc., being 

 increased in intensity. This can hardly be better illustrated than by 

 the following quotation from Tyndall, in which modern researches have 

 been applied to the vowel-sounds of the English language : 



" For the production of the sound U (oo in hoop), I must push my 

 lips forward so as to make the cavity of the mouth as deep as possible, 

 at the same time making the orifice of the mouth small. This arrange- 

 ment corresponds to the deepest resonance of which the mouth is 

 capable. The fundamental tone of the vocal chords is here reenforced, 

 while the higher tones are thrown into the shade. The U is rendered a 

 little more perfect when a feeble third tone is added to the fundamental. 



" The vowel O is pronounced when the mouth is so far opened that 

 the fundamental tone is accompanied by its strong higher octave. A 

 very feeble accompaniment of the third and fourth is advantageous, but 

 not necessary. 



" The vowel A derives its character from the third tone, to strengthen 

 which by resonance the orifice of the mouth must be wider, and the vol- 

 ume of air within it smaller than in the last instance. The second tone 

 ought to be added in moderate strength, whilst weak fourth and fifth 

 tones may also be included with advantage. 



" To produce E the fundamental tone must be weak, the second tone 

 comparatively strong, the third very feeble, but the fourth, which is 

 characteristic of this vowel, must be intense. A moderate fifth tone may 

 be added. No essential change, however, occurs in the character of the 

 sound when the third and fifth tones are omitted. In order to exalt 

 the higher tones which characterize the vowel-sound E t the resonant 

 cavity of the mouth must be small. 



" In the production of the sound ah ! the higher overtones come 

 principally into play ; the second tone may be entirely neglected ; the 

 third rendered very feebly ; the higher tones, particularly the fifth and 

 seventh, being added strongly. 



" These examples sufficiently illustrate the subject of vowel-sounds. 

 We -may blend in various ways the elementary tints of the solar spec- 

 trum, producing innumerable composite colors by their admixture. Out 

 of violet and red we produce purple, and out of yellow and blue we 

 produce white. Thus also may elementary sounds be blended so as to 

 produce all possible varieties of clang-tint. After having resolved the 

 human voice into its constituent tones, Helmholtz was able to imitate 

 these tones by tuning-forks, and, by combining them appropriately 

 together, to produce the clang-tints of all the vowels." 



