Hawaii Institute of Marine Biology, University of Hawaii, 46-007 Lilipuna Road, Kaneohe, Hawaii 96744, USA.
Department of Otology and Laryngology, Harvard Medical School, Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
J Acoust Soc Am. 2018 May;143(5):2611. doi: 10.1121/1.5034464.
Bottlenose dolphins project broadband echolocation signals for detecting and locating prey and predators, and for spatial orientation. There are many unknowns concerning the specifics of biosonar signal production and propagation in the head of dolphins and this manuscript represents an effort to address this topic. A two-dimensional finite element model was constructed using high resolution CT scan data. The model simulated the acoustic processes in the vertical plane of the biosonar signal emitted from the phonic lips and propagated into the water through the animal's head. The acoustic field on the animal's forehead and the farfield transmission beam pattern of the echolocating dolphin were determined. The simulation results and prior acoustic measurements were qualitatively extremely consistent. The role of the main structures on the sound propagation pathway such as the air sacs, melon, and connective tissue was investigated. Furthermore, an investigation of the driving force at the phonic lips for dolphins that emit broadband echolocation signals and porpoises that emit narrowband echolocation signals suggested that the driving force is different for the two types of biosonar. Finally, the results provide a visual understanding of the sound transmission in dolphin's biosonar.
宽吻海豚通过宽带回声定位信号来探测和定位猎物和捕食者，并进行空间定位。关于海豚头部生物声纳信号产生和传播的具体细节还有许多未知之处，本手稿代表了对此主题的研究努力。利用高分辨率 CT 扫描数据构建了二维有限元模型。该模型模拟了从声唇发出并通过动物头部传播到水中的生物声纳信号在垂直平面内的声学过程。确定了动物额头上的声场和回声定位海豚的远场传输波束模式。模拟结果与先前的声学测量结果在定性上非常一致。研究了气囊、甜瓜和结缔组织等主要结构在声音传播路径中的作用。此外，对发射宽带回声定位信号的海豚和发射窄带回声定位信号的鼠海豚的声唇驱动力进行了研究，结果表明这两种生物声纳的驱动力不同。最后，结果提供了对海豚生物声纳中声音传输的直观理解。
