01782nas a2200181   4500008004100000022001400041245008200055210006900137260001600206300001600222490000800238520122000246100002001466700002001486700002101506700002201527856005101549       2018                        eng d  a0001-496600aDifferential hearing sensitivity in the adaptive background in a beluga whale0 aDifferential hearing sensitivity in the adaptive background in a  cJan-09-2018  a1979 - 19790 v1443 a<p>The ability of the auditory system to maintain high differential sensitivity in the adaptive background was investigated in a beluga whale (Delphinapterus leucas). Adaptive background was a train of tone pips following one another at a rate of 1 kHz. Each pip consisted of eight carrier cycles of 64 kHz. Every 128 ms, the train of pips was interrupted for 16 ms and replaced with a test signal (16-ms series of the same tone pips as in the adaptive background, but of another level). The level of the test signals varied from -15 to +&thinsp;20 dB relative the level of adaptive background. Evoked potentials (the rate following response, RFR) produced by the test signals were recorded. Increasing of adaptive level led to RFR thresholds growth. The 10-dB rising of adaptive signals intensity level led to 7.8 dB rising of test signal threshold. The response amplitude dependence on the test stimulus level was almost independent of the level of the adaptive background. Thus, the beluga&rsquo;s auditory system displayed high sensitivity to the change in acoustic signal level in the high-level background. [This study was supported by the Russian Foundation for Basic Research (Grant No. 18-04-00088).]</p>
1 aPopov, Vladimir1 aNechaev, Dmitry1 aSupin, Alexander1 aSysueva, Evgeniya  uhttp://asa.scitation.org/doi/10.1121/1.506864301725nas a2200181   4500008004100000022001400041245010400055210006900159260001600228300001600244490000800260520114100268100002201409700002001431700002101451700002001472856005101492       2018                        eng d  a0001-496600aResponses of the auditory system of odontocetes to level changes of long lasting acoustical stimuli0 aResponses of the auditory system of odontocetes to level changes  cJan-09-2018  a1741 - 17410 v1443 a<p>The effects of level changes of long lasting sound stimuli (tone pip trains) on evoked potentials (the rate following response, RFR) were investigated in a beluga whale (Delphinapterus leucas). The stimuli were of 64 kHz carrier frequency at levels from 80 to 140 dB re 1 &mu;Pa. During stimulation, the stimulus level either was kept constant (the steady-state stimulation) or was changed up/down by 20 or 40 dB every 1000 ms. After transition from a lower to upper stimulus level (increase), the response amplitude increased quickly and then decayed slowly. After transition from an upper to lower stimulus level (decrease), the response amplitude fell quickly and later recovered slowly. In the both cases, during the 1000 ms stimulus, the response amplitude almost reached that of the steady-state stimulus of the same level. The auditory system of the beluga (and, hypothetically, other odontocetes) may be characterized as quickly flexible and capable of quick adjustment of its responses to the current auditory scene. [This study was supported the Russian Science Foundation (Project No. 17-74-20107) awarded to E.V.S.]</p>
1 aSysueva, Evgeniya1 aNechaev, Dmitry1 aSupin, Alexander1 aPopov, Vladimir  uhttp://asa.scitation.org/doi/10.1121/1.5067719