hing, without throwing the cords into vibration enough to
produce any sound.

We may say that the production of the voice is effected by an arrangement
like that of some musical instruments, the sounds produced by the
vibrations of the vocal cords being modified by the tubes above and below.
All musical sounds are due to movements or vibrations occurring with a
certain regularity, and they differ in loudness, pitch, and quality.
Loudness of the sound depends upon the extent of the vibrations, pitch on
the rapidity of the vibrations, and quality on the admixture of tones
produced by vibrations of varying rates of rapidity, related to one
another.

[Illustration: Fig. 151.--Longitudinal Section of the Larynx. (Showing the
vocal cords.)

A, epiglottis;
B, section of hyoid bone;
C, superior vocal cord;
D, ventricle of the larynx;
E, inferior vocal cord;
F, section of the thyroid cartilage;
H, section of anterior portion of the cricoid cartilage;
K, trachea;
L, section of the posterior portion of the cricoid cartilage;
M, arytenoid cartilage;
N, section of the arytenoid muscle.
]

353. Factors in the Production of the Voice. Muscles which pass from
the cricoid cartilage to the outer angle of the arytenoids act to bring
the vocal cords close together, and parallel to one another, so that the
space between them is narrowed to a slit. A strong expiration now drives
the air from the lungs through the slit, between the cords, and throws
them into vibration. The vibration is small in amount, but very rapid.
Other muscles are connected with the arytenoid cartilages which serve to
seperate the vocal cords and to widely open the glottis. The force of the
outgoing current of air determines the extent of the movement of the
cords, and thus the loudness of the sound will increase with greater force
of expiration.

We have just learned that the pitch of sound depends on the rapidity of
the vibrations. This depends on the length of cords and their tightness
for the shorter and tighter a string is, the higher is the note which its
vibration produces. The vocal cords of women are about one-third shorter
than those of men, hence the higher pitch of the notes they produce. In
children the vocal cords are shorter than in adults.[50] The cords of
tenor singers are also shorter than those of basses and baritones. The
muscles within the larynx, of course, play a very important part in
altering the tension of the