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Dolphin Sonar Signals: flexibilitiy and fine control

Clicks might seem like very simple signals, especially compared with the tonal signals of bats. In fact, dolphins excercise fine control over the exact structure of their clicks.

These diagrams each show the power spectra of a train of clicks. The click trains last just over a second. The power sprectrum of the first click is at the bottom, and you can see the spectra of many clicks running up the diagonal axis.

The figures are adapted from "The Sonar of Dolphins" by Whitlow Au (1993)

In this click train, the sprectra vary randomly, and the dolphin seems to show no control over its clicks. Some clicks have a lot of high frequency energy, some don't.

In this click train, the spectrum of each click is almost exactly the same as that of the previous click, each having most energy at about 110 kHz. The dolphin seems to maintain its clicks in a constant form.