Popov Vladimir V, Supin Alexander Ya, Gvozdeva Alisa P, Nechaev Dmitry I, Tarakanov Mikhail B, Sysueva Evgeniya V
Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, Moscow 119071, Russia.
Sechenov Institute of Evolutionary Physiology and Biochemistry Russian Academy of Sciences, 44 Torez Prospect, Saint-Petersburg 194223, Russia.
J Acoust Soc Am. 2020 Mar;147(3):1719. doi: 10.1121/10.0000909.
The impact of maskers on the receiving beam of a bottlenose dolphin, Tursiops truncatus, was investigated using the auditory evoked potential (AEP) method. The test signal was a train of tone pips with a 64 kHz carrier frequency. The stimulus produced AEPs as a sequence of waves replicating the pip rate: the rate following response (RFR). The masker was band-limited noise, with a passband of 45 to 90 kHz and a level of 105 dB re 1 μPa. Masker azimuths were at 0°, ±30°, ±60°, and ±90° relative to the head midline. The receiving beam was evaluated in terms of the RFR threshold dependence on the signal azimuth. The masked thresholds were higher than the baseline thresholds, which appeared mostly as a shift rather than a deformation in the receiving beam. The largest threshold shift appeared when the masker source was located in the most sensitive direction (zero azimuth); at lateral masker source positions, the threshold shift decreased. When the masker source was not at the head midline, the masked thresholds were higher at signal positions ipsilateral to the masker source than at positions contralateral to the masker source. The largest asymmetry was observed at the 30° masker azimuth in conjunction with the ±30° and ±120° signal azimuths; the asymmetries were 5.6 and 8.1 dB, respectively. This masking asymmetry was lower than expected from the previously found interaural intensity difference, which may be explained by the conflict between the test signal and the masker when it appeared at a binaural level of the auditory system.
采用听觉诱发电位（AEP）方法研究了掩蔽声对宽吻海豚（Tursiops truncatus）接收波束的影响。测试信号是一系列载波频率为64 kHz的短纯音。该刺激产生的听觉诱发电位表现为一系列与短纯音速率相同的波：速率跟随反应（RFR）。掩蔽声为带限噪声，通带为45至90 kHz，声压级为相对于1 μPa为105 dB。掩蔽声方位相对于头部中线为0°、±30°、±60°和±90°。根据速率跟随反应阈值对信号方位的依赖性来评估接收波束。掩蔽阈值高于基线阈值，这主要表现为接收波束的偏移而非变形。当掩蔽声源位于最敏感方向（零方位）时，阈值偏移最大；在掩蔽声源的横向位置，阈值偏移减小。当掩蔽声源不在头部中线时，掩蔽阈值在掩蔽声源同侧的信号位置高于在掩蔽声源对侧的位置。在掩蔽声方位为30°且信号方位为±30°和±120°时观察到最大不对称性；不对称性分别为5.6 dB和8.1 dB。这种掩蔽不对称性低于根据先前发现的双耳强度差预期的值这可能是由于测试信号与掩蔽声在听觉系统双耳水平出现时的冲突所致。
