resonator forms the body of the vocal instrument. Every sound passes
through it; every vowel and consonant in the production of syllables and
words must be formed by it, and the whole character and individual
qualities of the speaking as well as the singing voice depend in great part
upon the manner in which it is used.

The acoustic effect is due to the resonances generated by hollow spaces of
the resonator, and Dr. Aikin, in his work on "The Voice," points out that
we can study the resonances yielded by these hollow spaces by whispering
the vocal sounds; but it is necessary to put the resonator under favourable
conditions for the most efficient production. When a vowel sound is
whispered the glottis is open (_vide_ fig. 10) and the vocal cords are not
thrown into vibration; yet each vowel sound is associated with a distinct
musical note, and we can produce a whole octave by alteration of the
resonator in whispering the vowel sounds. In order to do this efficiently
it is necessary to use the bellows and the resonator to the best advantage;
therefore, after taking a deep inspiration in the manner previously
described, the air is expelled through the open glottis into the resonating
cavity, which (as fig. 13 shows) is placed under different conditions
according to the particular vowel sound whispered. In all cases the mouth
is opened, keeping the front teeth about one inch apart; the tongue should
be in contact with the lower dental arch and lie as flat on the floor of
the mouth as the production of the particular vowel sound will permit. When
this is done, and a vowel sound whispered, a distinctly resonant note can
be heard. Helmholtz and a number of distinguished German physicists and
physiologists have analysed the vowel sounds in the whispering voice and
obtained very different results. If their experiments show nothing else,
they certainly indicate that there are no universally fixed resonances for
any particular vowel sound. Some of the discrepancies may (as Aikin points
out) be due to the conditions of the experiment not being conducted under