Time and frequency cues used by bottlenose dolphins for target discrimination

Gennadi Zaslavski

Dolphins echolocate by emitting very short clicks and processing the echoes returned by underwater objects. Although the ability of dolphins to detect and discriminate among underwater objects is well documented, the controversy over acoustic features of object echoes processed by the dolphins remains heated, as ever. Most of the target discrimination models in dolphins are based on frequency analysis of the target echoes. Furthermore, a long ago rejected notion about dolphins' ability to modify spectral content of outgoing click to fit specific echolocation task and target characteristics is becoming popular again. The biggest obstacle for the frequency domain models is dolphins' ability to discriminate between brief time-reversed signals having identical frequency spectra. To overcome this problem a short time-frequency analysis of target echoes in dolphins was suggested. However in order to fit existing behavioral experimental results with dolphins into the time-frequency model, an extremely high auditory time resolution has to be assumed in the first place. Some behavioral results indicating the bottlenose dolphin's auditory time resolution as high as about twenty microseconds will be discussed.

Domaines: Acoustique [physics.class-ph]

Gennadi Zaslavski. Time and frequency cues used by bottlenose dolphins for target discrimination. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810607⟩