may be a corresponding alteration in voice, as regards range,
power, and quality. The voice, because of imperfect anatomical and
physiological adjustment, may "break," to a greater or less extent.
The same may take place, owing to similar imperfect adjustment, in
old age, and temporarily, owing to disease, weakness, nervousness,
fatigue, faulty production, etc. These facts indicate that under such
circumstances the voice should be used with great care, not at all, or
in a whisper, when the vocal bands are practically not in action.

[Illustration: FIG. 45. Represents what the author has frequently
seen, by the use of the laryngoscope, when a soprano is producing a
very high head-tone, say C, D, or E in alt. It will be observed that
the vocal bands approximate in front and behind ("stopped"), so that
the only parts of the bands capable of vibration are those short
portions which form the margins of the oval opening shown in the
illustration. Only a very limited number of singers are capable of the
delicate adjustments required.]

In a singer highly endowed by nature and perfected by long training
based on the soundest principles, the action of the muscles of the
larynx may reach a degree of perfection only to be compared with that
of the eye and ear.

Consideration of the _coup de glotte_, the attack, or adjustment of
mechanisms to produce tone that begins correctly; breathing, with open
mouth, with effectiveness and economy of energy; singing for children,
in choirs, etc., have been discussed.

Practical exercises should be related to the principles underlying
them. Musical and aesthetic principles are always to be associated with
a sound technique. The artistic and technical or physiological
conscience should be associated.

CHAPTER IX.

THE RESONANCE-CHAMBERS.

When it is borne in mind that the vocal bands have little or nothing
to do with the quality of tones, the importance of those parts of the
vocal apparatus which determine quality, and the error of speaking of
the larynx as if it alone were the sole vocal organ, become apparent.

It may be strictly said that the vocal bands serve the purpose of
making the resonance mechanism available. What one hears may be said
to be vibrations of this resonance apparatus, and not, strictly, those
of the vocal bands, though this expression would also be correct, but
would not indicate the final link in the series of vibrations.

The tone caused by the vibrat