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THE NOI SY CICADA
The cicada is a noisy insect. It produces ticks, buzzes and whines by means
of a system in its body. There is a pair of membranous organs at the base
of the insect's abdomen. The cicada produces that well-known sound by vi-
brating these drum-like membranes. When these membranes are pulled and
released by the muscles to which they are attached, a sound similar to that
of an empty tin is produced. The insect repeats this pull-and-release process
500 times a second. Considering that you can only close and reopen your
eyes once in a second, you can readily see how difficult it is to perform this
task 500 times a second.
With the opening and closing of the extended part that exists on the lower
part of the insect's thorax, the sound level may be increased or decreased.
The human ear cannot perceive these openings and closings, which occur
in a tenth of a second, so we do not notice that the sound is interrupted
and we think that the buzzing song of the cicada is continuous.
W O N D E R F U L C R E A T U R E S
