USE OF CLICKS RESEMBLING THOSE OF THE ATLANTIC BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) WITH BIASED PULSE SUMMATION SONAR (BiaPSS) TO IMPROVE TARGET DISCRIMINATION IN BUBBLY WATER

Odontocetes (toothed whales) routinely produce pulsed sounds, which many studies have shown to be used for echolocation [1]. The deliberate production by dolphins of bubble nets suggested that their echolocation may function well in bubbly water that would confound man-made sonar [2,3], an observation supported by the outstanding sonar performance of such animals in shallow waters. A sonar scheme Twin Inverted Pulse Sonar (TWIPS) which exploited the fact that bubbles would scatter closely-spaced pairs of equal-amplitude pulses nonlinearly, whilst other targets would not [2], was developed and tested successfully at sea [4, 5]. However TWIPS worked because consecutive pulses had inverted phase, and the only pulses resembling these to be found in odontocetes have been recorded to date at amplitudes too low to be of use in such a processing scheme [4, 6]. Their origin is not certain and their purpose (if any) has also not been determined [6].