Abstract:

The sonar of dolphins may be the most sophisticated of all sonar systems, biological or man-made, in shallow waters and for short ranges. The Atlantic bottlenose dolphin emit short-duration (50--70 (mu)s), high-frequency (120--140 kHz), broadband (40--50 kHz) echolocation signals with peak-to-peak amplitudes up to 228 dB re: 1 (mu)Pa. The type of signals used by dolphins play a significant role in their sonar discrimination capabilities. They have been observed detecting, classifying, and retrieving prey that is buried in sandy bottom up to a depth of about 0.3 m. In addition, controlled echolocation experiments have shown that dolphins can discriminate wall thickness, material composition, shape, and size of targets. The echolocation system of dolphins will be discussed in three parts. The first part will consider the properties of the receiving system (auditory capabilities). The second part will deal with the characteristics of echolocation signals, and the third part will consider several sonar capabilities.