Animal echolocation and signal processing

The echolocation capabilities of dolphins and small whales exceed those of current man-made sonars. Dolphins, beluga whales and false killer whales can perceive small targets presented over 110 m away, can classify target shapes independent of internal target reverberation, can discriminate wall thickness differences in targets of less than .2 mm, and can operate in high noise environments. Recent natural observations indicate that several species may also detect and choose targets buried in sediment. These tasks are accomplished through the use of range-gated clicks that tend to be broad band with peak frequencies exceeding 100 kHz. The short (50 microsec) pulses can have amplitudes exceeding 220 db and bandwidths exceeding 60 kHz. This paper provides a short review of animal echolocation capabilities, methodologies used to examine them, and potential uses of neural networks and other signal processing techniques to understand and perhaps duplicate those animal capabilities. >