page 3 of 5 

Dolphin Sonar Signals

What do dolphin clicks sound like to us? The short duration of clicks makes them sound "dry". When scientists analyse the clicks, they appear to be very, very broad in bandwidth, meaning they contain energy at a wide range of frequencies. The bandwidth is so great that there is energy at frequencies up to 200 kHz, and also energy down at frequencies of 5-20 kHz, at which humans can hear the signals. This means we can only hear the very lowest frequency part of the click with the unaided ear. We can slow the sounds down, employing the method called time expansion, to hear the ultrasonic part of the signal.