650 ANIMAL PHYSIOLOGY. 
If a series of tuning-forks be held before the open mouth, 
it will be found that but one position of the buccal cavity and 
its contents answers to a certain note, but that when this is 
assumed it acts as a resonance-chamber; thus, for a tuning- 
fork sounding A, when the cavity takes the shape necessary 
to sound (speak) that note, the tone produced by the fork is 
greatly augmented when the latter is held before the mouth, * 
It has thus been estimated that the fundamental tones of the 
vowel cavity are these: U=b;O=b’, A=b’'’,I=b’”. If the 
vowels of this series be whispered, their pitch rises. "Whisper- 
ing may be termed speech without voice—i. e., the vocal bands 
do not vibrate, but the total effect is produced by the blast of 
air acting through the supra-laryngeal parts as a resonance 
cavity. 
Now, if it be true that there is but one position of the supra- 
laryngeal cavities that will give a pure vowel-sound, and this 
sound corresponds in pitch to a certain note of the scale, it 
seems to us that the conclusion that the pitch of the voice, as 
well as its quality, is dependent to some extent upon these parts 
as well as the vocal bands. Such a view is, however, not that 
generally taught. Every singer knows that it is impossible to 
produce certain vowel-sounds pure with notes of a certain pitch. 
Usually, when the nasal cavity is shut off posteriorly by the 
soft palate, or stopped anteriorly by closing the nostrils, a 
change in quality of the vowel-sounds, characterized as nasal, 
is produced ; but, as illustrating well that the organism has 
more ways than one of accomplishing the larger part if not all 
its ends, by effort, and especially by practice, the vowels may 
be sounded nearly as well as usual under these unfavorable 
conditions. 
Consonants.—The sounds produced by the vocal bands may 
be modified by interruption in their formation or otherwise, 
though it is plain, from what has been said, that the form of 
the mouth, etc., can not be ignored in any form of vocalization. 
According to the parts of the supra-laryngeal cavities con- 
cerned in the modification referred to, may we have the basis 
of a physiological classification of the consonants, though it is 
obvious that they may be dealt with on wholly different prin- 
ciples. By the first method, which alone chiefly concerns us, 
we have a division into labials, dentals, and gutturals, according 
as the lips, teeth, or soft palate and pharynx are chiefly con- 
cerned. Of course, several parts are involved in all sound-pro- 
duction, and we recommend the student to resort to the forma- 
