high tones, these, with their inherent capacity for penetration,
probably would become disagreeably acute. Therefore, nature, wise in
this as in many other things, has decreased chest vibration as the voice
ascends the scale.

Above the larynx is the pharynx, a space extending to the base of the
skull and opening into the mouth, and higher up connecting with the base
of the nose by means of two passages, the posterior nares, or back nasal
passages. The walls of the pharynx are permeated by a network of muscles,
so that this important space or resonance-cavity immediately above the
larynx is susceptible of numerous adjustments and readjustments in size
and shape; and as it lies with its back wall against the spinal column,
it also is susceptible and immediately responsive to suggestion from
the mind.

Another important resonance-cavity, indeed, the most important, is the
mouth, roofed by the hard palate which separates the mouth from the
nasal chamber, to which latter it also forms the floor. In the mouth is
the tongue, extremely mobile, and thus capable of materially changing
the size and shape of the mouth-cavity. Hanging from the rear of the
hard palate, like a veil over the root of the tongue, is the soft
palate; attached to which is the uvula. This hangs vertically down from
the soft palate and, if the rear end of the tongue is allowed to bulge
upward slightly, can be made to form with it a kind of valve, by which
voice is conveyed directly into the mouth-cavity without any of it
escaping up the posterior nasal passage; while the soft palate by itself
alone can be drawn up so as to touch the back wall of the pharynx,
completely closing the passage to the nose, so that a continuous curved
resonance-cavity is afforded from larynx to lips.

The soft palate is continued on either side by two folds known as the
fauces; and each of the fauces has two ridges, the pillars of the
fauces, between which are the tonsils. The pillars of the fauces enclose
muscular fibres which act respectively on the tongue, the sides of the
pharynx, and the upper part of the larynx, and thus aid in the necessary
movements of the vocal tract.

The nasal passage, divided into two ducts by a vertical partition, the
_vomer septum_, was referred to in the chapter on inspiration. The
so-called sinuses are hollow spaces in small bones on either side and
above the nasal passage and communicating directly or indirectly with
it. A question regarding