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How do bats avoid hitting themselves in the caves?
Bats tell where they are by a special biological adaptation - a really
good ear (also known as 'sonar' or 'echo location'). They make a noise
that is just on the edge of human hearing but is very easy for them to
hear. Then they listen to the echos of the sound. They know how close
or how far away things are by listening to how long it takes for the
sound to return to them.
Think of a time when you heard an echo of your voice. You may have
noticed that it takes longer for you to hear an echo in a big room.
This is because the soundwaves from your voice have to travel all the
way to something and then all the way back before you hear them. This
is exactly what bats pay attention to. The sooner they hear an echo,
the closer they must be to a wall.
(republished on 07/18/06)
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