hispered 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
the same conditions. Aikin, indeed, asserts that if the directions given
above be fulfilled, there will be variations between full-grown men and
women of one or two tones, and between different men and different women of
one or two semi-tones, and not much more. As he truly affirms, if the tube
is six inches long a variation of three-quarters of an inch could only make
a difference of a whole tone in the resonance, and he implies that the
different results obtained by these different experimenters were due to the
faulty use of the resonator.

In ordinary conversation much faulty pronunciation is overlooked so long as
the words themselves are intelligible, but in singing and public speaking
every misuse of the resonator is magnified and does not pass unnoticed.
Increased loudness of the voice will not improve its carrying power if the
resonator is improperly used; it will often lead to a rise of pitch and the
production of a harsh, shrill tone associated with a sense of strain and
effort. Aikin claims that by studying the whispering voice we can find for