The light from the lamp is reflected by the concave mirror on to the
small mirror, which, owing to its angle of 45 deg., illuminates the glottis and
reflects the image of the glottis with the vocal cords.]
The discovery of the laryngoscope by Garcia enabled him by its means to see
the vocal cords in action and how the reed portion of the vocal instrument
works (_vide_ fig. 9 and description). The chink of the glottis or the
opening between the vocal cords as seen in the mirror of the laryngoscope
varies in size. The vocal cords or ligaments appear dead white and contrast
with the surrounding pink mucous membrane covering the remaining structures
of the larynx. Fig. 10 shows the appearance of the glottis in respiration
and vocalisation. The vocal cords of a man are about seven-twelfths of an
inch in length, and those of a boy (before the voice breaks) or of a woman
are about five-twelfths of an inch; and there is a corresponding difference
in size of the voice-box or larynx. This difference in length of the vocal
cords accounts for the difference in the pitch of the speaking voice and
the register of the singing voice of the two sexes. We should also expect a
constant difference in the length of the cords of a tenor and a bass in the
male, and of the contralto and soprano in the female, but such is not the
case.
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