How do bats see with the help of sound ?
Let us now understand how they find and capture insects at night.
They emit out a sound, so high that we cannot hear it.
A high sound means large frequency.
A low sound means small frequency.
We earlier talked of frequency being measured in Hz. Human beings can hear frequencies from 20 Hz to 20, 000 Hz. Bats produce sounds of frequency 30,000 Hz to about 120,000 Hz. Lowest sound they produce is much higher than the highest sound we can hear!
Most bats produce these sounds from their mouth. Some bats can even produce such sounds though their nose .
The sound waves which they produce travel all around them. If there happens to be an insect (say , a moth ) somewhere around, the waves bounce off its body and come back to the bat just like the echo of your voice in a hall.
A bat collects these returning waves in his ears which are also extra ordinary.
In the picture below, see how big their ears are. They are twice the size of their head, much better than ours to collect and hear these high echo sounds coming back. They can also turned and tilted in various ways.
Now, what you will find interesting is the so many things that a bat can tell just by hearing the echo of its own sound.
Let us see what all can a bat tell about its prey by listening to the echo coming from it.