時 間：10月14日（星期三）15:00-17:00
主 講：Whitlow W.L Au教授（美國夏威夷大學海洋生物研究所 鯨豚生物聲學領域國際權威）
地 點：周隆泉樓B3-202教室
摘要：Dolphins have a very sophisticated short range sonar that surpass all technological sonar in its capabilities to perform complex target discrimination and recognition tasks. The system that the U.S. Navy has for detecting mines buried under ocean sediment is one that uses Atlantic bottlenose dolphins. However, close examination of the dolphin sonar system will reveal that the dolphin acoustic “hardware” is fairly ordinary and not very special. The transmitted signals have peak-to-peak amplitudes as high as 225 - 228 dB re 1 ?Pa which translate to an rms value of approximately 210 - 213 dB. The transmit beamwidth is fairly broad at about 10o in both the horizontal and vertical planes and the receiving beamwidth is slightly broader by several degrees. The auditory filters are not very narrow with Q values of about 8.4. Despite these fairly ordinary features of the acoustic system, these animals still demonstrate very unusual and astonishing capabilities. The dolphin biosonar system will be discussed from the perspective of a technological sonar system consisting of a signal projection section including signal generation, propagation through the head and directivity index, a reception section including receiving sensitivity, directivity, and internal filtering process, and a signal processing section.
Some of the capabilities of the dolphin sonar system will be presented and the reasons for their keen sonar capabilities such as discriminating and recognizing different fish species, differences in wall thickness of metal cylinders and differences in the composition of metallic targets will be discussed. Important features of their sonar include the broadband click-like signals used, adaptive sonar search capabilities and large dynamic range of its auditory system.
專家簡介：Whitlow W.L Au教授是夏威夷大學海洋生物研究所海洋哺乳動物研究項目首席科學家，是世界鯨豚生物聲納研究領域的權威專家，在國際上享有極高的知名度。1998年他因對海豚聲納基礎聲學的卓越貢獻而榮獲美國聲學學會動物聲學銀獎（該獎項設立以來首位獲獎人）。此外，他長期擔任《美國聲學學會雜志》、《動物生物聲學》等雜志的副主編，還曾擔任美國聲學學會理事長，美國聲學學會、動物聲學技術委員會聯合主席。在學術成果方面，他曾出版過3本關于海洋哺乳動物聲學研究的著作及多達數百篇學術論文，其中他的專著《The Sonar of Dolphins》已成為海豚生物聲納領域的經典著作。
