Acoustics and Sonar, Netherlands Organization for Applied Scientific Research (TNO), P.O. Box 96864, The Hague 2509 JG, The Netherlands.
Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom.
J Acoust Soc Am. 2021 Apr;149(4):2908. doi: 10.1121/10.0004769.
Modern active sonar systems can (almost) continuously transmit and receive sound, which can lead to more masking of important sounds for marine mammals than conventional pulsed sonar systems transmitting at a much lower duty cycle. This study investigated the potential of 1-2 kHz active sonar to mask echolocation-based foraging of sperm whales by modeling their echolocation detection process. Continuous masking for an echolocating sperm whale facing a sonar was predicted for sonar sound pressure levels of 160 dB re 1 μPa, with intermittent masking at levels of 120 dB re 1 μPa, but model predictions strongly depended on the animal orientation, harmonic content of the sonar, click source level, and target strength of the prey. The masking model predicted lower masking potential of buzz clicks compared to regular clicks, even though the energy source level is much lower. For buzz clicks, the lower source level is compensated for by the reduced two-way propagation loss to nearby prey during buzzes. These results help to predict what types of behavioral changes could indicate masking in the wild. Several key knowledge gaps related to masking potential of sonar in echolocating odontocetes were identified that require further investigation to assess the significance of masking.
现代主动声纳系统可以（几乎）连续地发射和接收声波，这可能导致海洋哺乳动物比传统的脉冲声纳系统在发射时具有更低的占空比更容易被重要声音掩盖。本研究通过模拟抹香鲸的回声定位探测过程，研究了 1-2 kHz 主动声纳掩盖其回声定位觅食的潜力。研究预测，当面对声纳时，连续掩蔽抹香鲸的声压级为 160 dB ，间歇性掩蔽声压级为 120 dB ，但模型预测强烈依赖于动物的方向、声纳的谐波含量、点击源级和猎物的目标强度。掩蔽模型预测，即使能量源级低，嗡嗡声比常规声纳脉冲的掩蔽潜力低。对于嗡嗡声，由于在嗡嗡声期间到附近猎物的双向传播损失减少，因此较低的声源级得到补偿。这些结果有助于预测在野外什么类型的行为变化可能表明存在掩蔽现象。研究还确定了一些与回声定位齿鲸声纳掩蔽潜力相关的关键知识空白，需要进一步研究以评估掩蔽的意义。
