In Africa, all insect-eating bats, and one species of cave-dwelling fruit bat, the Egyptian fruit bat, communicate
and navigate using echoes bounced back from high frequency, ultrasonic clicks and squeaks emitted through the mouth or nostrils, a
system known as echolocation.
The ultrasonic calls emitted by bats range in frequency (‘pitch’) from 20 to 210 kilohertz (one
kilohertz, or 1 kHz, equals 1000 vibrations per second) and are generally inaudible to humans (who hear sounds of up to 20 kHz). Even
though we cannot hear them, bats’ echolocation calls vary considerably in amplitude, with ‘whispering bats’ having soft calls and
bats like horseshoe bats having very loud calls, with amplitudes comparable to the sound of a jackhammer at close range.
The echolocation system of bats is vastly more efficient than any man-made sonar system. The American Navy is conducting ongoing research
into the echolocation system of bats so as to model their underwater sonar systems more closely on that of bats.
Today we can
use bat detectors to convert the higher pitched bat sounds into signals that we can hear. This provides us with a window on the fascinating
lives of bats