EAPSI: Measuring the hearing and echolocation characteristics of a Risso's dolphin

所有的齿鲸和海豚都拥有高度发达的听觉和生物声纳系统，即使是现代技术也无法复制。这些特殊的能力是头部极其特殊的解剖结构的结果。更好地了解齿鲸的这些系统可能会导致信号处理、声纳技术、医学成像设备和耳蜗植入技术的进步。有一种叫做瑞索海豚的海豚，在它的额头上进化出了一种独特的垂直折痕，这在其他海豚物种中是没有的。虽然这个皱褶的功能尚不清楚，但它在头部的位置表明它可能在听觉或回声定位系统中起着重要作用。对这些系统的详细研究需要训练有素的圈养实验动物的合作。该项目将与台湾国立嘉义大学的杨伟成博士合作，通过测量台湾花莲Farglory海洋公园一只经过训练的圈养里索海豚的听力和回声定位声音来研究瓜纹的功能，这只海豚是世界上仅有的三只圈养里索海豚之一。本项目拟进行的实验将1)测量动物对头部不同位置声刺激的听觉灵敏度，2)测量回声定位波束在近声场和远声场中的声学特性。听力测量将使用非侵入性听觉脑干反应（ABR）方法进行，该方法测量来自脑干的神经脉冲对声音接收的反应。回声定位波束在近场和远场的模式将被记录使用一个可变阵列的同步水听器。这项研究将首次描述瑞索海豚的听觉通路和回声定位波束模式，也是研究瓜裂的功能形态的第一步。​

All toothed whales and dolphins possess highly developed hearing and biosonar systems that cannot be replicated even with modern technology. These exceptional capabilities are the result of extremely specialized anatomical structures in the head. A better understanding of these systems in toothed whales may lead to improved technological advancements for signal processing, sonar techniques, medical imaging devices, and cochlear implants. One species of dolphin, the Risso's dolphin, has evolved a unique vertical crease on its forehead which is absent in other dolphin species. Although the function of this crease is unknown, its location on the head indicates it likely plays an important role in the hearing or echolocation systems. Detailed study of these systems requires the cooperation of a trained captive subject animal. In collaboration with Dr. Jack Wei-Cheng Yang at National Chiayi University in Taiwan, this project will investigate the function of the melon crease by measuring the hearing capabilities and echolocation sounds of a trained captive Risso's dolphin at Farglory Ocean Park in Hualien, Taiwan, one of only three captive individuals of this species in the world. Proposed experiments for this project will 1) measure the hearing sensitivities of the animal to acoustic stimuli presented at different points on the animal's head, and 2) measure acoustic characteristics of the echolocation beam in the near and far sound field. Hearing measurements will be conducted using non-invasive Auditory Brainstem Response (ABR) methodology, which measures nerve impulses from the brainstem in response to the reception of sound. Echolocation beam patterns in the near and far field will be recorded using a variable array of synchronized hydrophones. The proposed study would represent the first description of the hearing pathways and echolocation beam patterns in the Risso's dolphin and the first step toward studying the functional morphology of the melon cleft. This NSF EAPSI award is funded in collaboration with the National Science Council of Taiwan.