Page 79 - Design in Nature

a bat could detect the presence of a caterpillar on the floor. It emitted about

twenty thousand cycles in a second and could analyse all the reflected
sounds. Furthermore, while it carried out this task, the bat itself travelled.
Careful consideration of all these facts clearly reveals the miraculous design
in their creation.
Another stunning feature of bats' echolocation is the fact that the

hearing of bats has been created such that they cannot hear any other sounds
than their own. The spectrum of frequencies audible to these creatures is
very narrow, which would normally create a great problem for the animal
because of the Doppler Effect. According to the Doppler Effect, if the source
of sounds and the receiver of sounds are both relatively stationary, the
receiver will detect the same frequency as the source emits. However, if one

or the other is moving, the detected frequency will be different than the
emitted frequency. In this case, the frequency of the reflected sound could
fall into the spectrum of frequencies inaudible to the bat. The bat, therefore,