1897-98.] Prof. M‘Kendriek on Theories of Vowel Sounds. 71 
Observations on the Theories of Vowel Sounds. By John 
G. M ‘Kendrick, Professor of Physiology in the University 
of Glasgow. 
(Read February 7, 1898.) 
The quality of the human voice depends on the same laws as 
those determining the quality, klang-tint, or timbre of the tones 
produced by any musical instrument. Tones of a mixed char- 
acter, that is to say, composed of a fundamental and partials, are 
produced by the vibrations of the true vocal cords, and certain of 
those partials are strengthened by the resonance of the air in the 
air-passages, and in the pharyngeal and oral cavities. 
So strongly may certain of these partials be reinforced, as to 
obscure or hide the fundamental tone, and give a peculiar char- 
acter to the sound. These, however, are only general statements, 
and there are still many difficulties in the way of a true interpre- 
tation of voice-tones. In the first place, we observe that we may 
sing a scale, using one sound for each note, such as la , la , la , etc. 
Or, by putting the mouth in a certain position, we can pronounce 
the so-called vowels, a , e, i, o, u ( ou as the u in prune ), uttering 
the sounds ah, a, e, o, ou. As we do so, we notice that each sound 
appears to the ear to have a pitch of its own, different from that 
of the others. Thus, Helmholtz* gave the pitch of the vowel- 
tones as follows : — 
Vowels, . . 
ou 
0 
A 
A I 
E 
i 
EU 
u 
Tone, . . 
fa 2 
si b 3 
si b4 
sol 5 
si b 5 
re 6 
do 5 
sol 5 
or 
or 
or 
or 
or 
re 4 
fa 3 
fa 2 
fa 3 
fa 2 
Ho. of vibs., 
170 
470 
940 
1536 
1920 
2304 
1024 
1536 
or 
or 
or 
or 
or 
576 
341 
170 
341 
170 
* Helmholtz, Sensations of Tone, trans. by Ellis, 1875, p. 165 ; see also same 
work, p. 163, footnote 1, for result obtained by Merkel, Reyher, Hellwag, 
Florcke, and Donders. 
