tion. These are the mental
imitation of the tone, the imagined adjustments of the vocal organs, and
the imaginative exercise of the muscular sense. Although simultaneously
performed, each of these four operations may be considered separately.

_Hearing_

As the judgment of vocal tones by sympathetic sensations is purely a
function of the sense of hearing, the keenness of these sensations
varies in each individual in proportion to the keenness of the ear. It
would be a great mistake to assert that we all feel these sympathetic
sensations with equal vividness. On the contrary, many people are so
inattentive to the qualities of sounds that they hardly know the meaning
of the term "nasal tone."

One trait in particular distinguishes the musician and the music lover;
this is, the possession of a keen sense of hearing. The ear is trained
by exercise in its own function,--hearing. The more attentively we
listen to music the higher do we develop our ability to discriminate
between musical sounds. Moreover, natural endowments vary in different
individuals, with regard to the ear, as with all other human faculties.
To appreciate fully the wonderful insight into vocal operations conveyed
by the sympathetic sensations of tone, a naturally keen musical ear is
required; further, this natural gift of a good ear must be developed by
attentive listening to music, vocal and instrumental, carried on through
several years.

_Mental Imitation of Vocal Tones_

That every sense has its counterpart in the imagination need hardly be
said. We know what it means to feel warm or cold, hungry or thirsty; we
know the taste of an apple, the scent of a rose. We can at will create
pictures before the mind's eye. In the same way we can hear in
imagination any sound we choose to produce mentally.

An inseparable function of the sense of hearing is the impulse to
imitate mentally the tones of speakers and singers. The imitation of
sounds is an instinctive operation. "Talking proper does not set in till
the instinct to _imitate sounds_ ripens in the nervous system." (_The
Principles of Psychology_, Wm. James, N. Y., 1890.) Little can be said
about the impulse to imitate voices mentally, further than that it is an
exercise of this same instinct.

_Imagined Adjustments of the Vocal Organs_

It has already been seen that the vocal organs have the ability to
adjust themselves, through instinctive guidance, for the production of
any tone demanded by t