The time resolution of the dolphin's sonar: what is actual? [abstract]

G.L. Zaslavskiy (1998). The time resolution of the dolphin's sonar: what is actual? [abstract]. Bioacoustics, Volume 9 (3): 235

The time resolution constant for Tursiops truncatus clicks is between 12 and 15 µs (Au 1993). However this extremely high theoretical value has never been considered as the actual time resolution of the dolphin auditory system. The "critical interval'' of 260 + 25 µs as a measure of the time resolution was derived from the series of echolocation and hearing experiments on dolphin discrimination between correlated stimuli (Dubrovskiy and Velmin, 1975). Having learned by experience how wrong one could be in construing results of dolphin's discrimination of correlated stimuli, we introduced uncorrelated noise stimuli (Zaslavskiy, Ryabov and Titov 1979, Zaslavskiy and Ryabov, 1991). The temporal masking, time intervals and pulse envelopes discrimination for the noise stimuli were studied. The actual time resolution of dolphin's auditory system of about 20-30 µs consistently manifested itself from these experiments. The dolphins have shown remarkable capability in analysing different characteristics of very short pulses in the time domain. The time resolution of the dolphin auditory system proved to be practically equal to the theoretical time resolution of echolocation clicks and at least ten times shorter than auditory integration time (Au 1993). Results gave no indication of the "critical interval". Experimental data were collected at the Karadag Department of Institute of Biology of Southern Seas, Crimea, USSR in 1977- 1989.