phenomenon called the "movable break," which has puzzled so many in
their investigations of the registers of the child's voice. The
constant, though of course extremely slow, hardening of the
cartilaginous portions of the larynx, and the steady increase in the
strength of its muscles and ligaments is not in the least inconsistent
with the previously noted fact, that the vocal bands during this time
increase to no appreciable extent in length; for, it may be observed,
after the change of voice, which often occurs with great rapidity, and
during which the vocal bands increase to double their previous length in
males, that, though the pitch of the voice, owing to increased length of
the bands, suddenly lowers, yet not until full maturity is reached, do
the laryngeal cartilages attain that rigidity, or the vocal bands that
ready elasticity essential to the production of pure, resonant voice.
Yet, during these years, while the voice is developing, the vocal bands
remain unchanged in _length_. Even in those cases where the voice
changes slowly in consequence of the slow growth in length and thickness
of the vocal cords, it takes several years, after laryngeal development
has ceased, for the voice to attain its full size and resonance.

Furthermore, the continual increase in strength and firmness of the
larynx from six years onward to puberty, is consistent with the constant
growth in strength and firmness of tissue characterizing the entire
body. It is again proven by the continual improvement in the power and
timbre of the tone through this period, always premising, be it
understood, that the voice is used properly, and never forced beyond its
natural capabilities. The voice, at the age of eleven or twelve, is far
stronger, and is capable of more sustained effort than at the age of six
or seven years, and, for the year or two preceding the break of voice,
the brilliance and power of boys' voices, especially in the higher
tones, is often phenomenal, and in all cases is far superior to that of
previous years.

The resemblance between the voices of boys and girls, a resemblance
which amounts to identity, save that the voices of boys are stronger and
more brilliant in quality, disappears at puberty.

Among the physical changes which occur at this period is a marked growth
of the larynx, sufficient to alter entirely the pitch and character of
the boy's voice. As a female larynx is affected to a lesser extent, the
voices of gi