| Autor: |
Popov VV; Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, Moscow 119071, Russia., Supin AY; Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, Moscow 119071, Russia., Nechaev DI; Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, Moscow 119071, Russia., Lemazina AA; Max Plank Institute for Ornitology, Eberhard-Gwinner-Straße, 82319 Seewiesen, Germany., Sysueva EV; Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, Moscow 119071, Russia. |
| Abstrakt: |
In a beluga whale, the positions of sound receiving areas on the head surface were determined by comparing the acoustic delays from different sound source positions. For this investigation, auditory evoked potentials (AEPs) in response to short tone pips were recorded. Latencies of the first AEP wave that presumably reflected the activity of the auditory nerve were measured at different sound source azimuths. For AEPs of equal amplitudes, the difference in AEP latencies was attributed to the difference in the acoustic delays. These delay differences were used to compute the azimuths of sound receiving points. Measurements were conducted at frequencies from 22.5 to 90 kHz in half-octave steps. At all stimulus frequencies, the receiving points were located 24-38 cm caudal of the melon tip, which is near a proximal part of the lower jaw. Thus, the results indicated the latero-mandibular acoustic window. Possible causes for not finding a lateral or ventro-mandibular window are discussed. |
