*Article* **A Case Study of Whistle Detection and Localization for Humpback Dolphins in Taiwan**

**Ching-Tang Hung, Wei-Yen Chu, Wei-Lun Li, Yen-Hsiang Huang, Wei-Chun Hu and Chi-Fang Chen \***

Department of Engineering Science and Ocean Engineer, National Taiwan University, Taipei City 10216, Taiwan; d08525005@ntu.edu.tw (C.-T.H.); r06525012@ntu.edu.tw (W.-Y.C.); r05525004@ntu.edu.tw (W.-L.L.); r05525002@ntu.edu.tw (Y.-H.H.); d03525001@ntu.edu.tw (W.-C.H.)

**\*** Correspondence: chifang@ntu.edu.tw; Tel.: +886-2-3355-5735

**Abstract:** In recent years, Taiwan's government has focused on policies regarding offshore wind farming near the Indo-Pacific humpback dolphin habitat, where marine mammal observation is a critical consideration. The present research developed an algorithm called National Taiwan University Passive Acoustic Monitoring (NTU\_PAM) to assist marine mammal observers (MMOs). The algorithm performs whistle detection processing and whistle localization. Whistle detection processing is based on image processing and whistle feature extraction; whistle localization is based on the time difference of arrival (TDOA) method. To test the whistle detection performance, we used the same data to compare NTU\_PAM and the widely used software PAMGuard. To test whistle localization, we designed a real field experiment where a sound source projected simulated whistles, which were then recorded by several hydrophone stations. The data were analyzed to locate the moving path of the source. The results show that localization accuracy was higher when the sound source position was in the detection region composed of hydrophone stations. This paper provides a method for MMOs to conveniently observe the migration path and population dynamics of cetaceans without ecological disturbance.

**Keywords:** marine mammal; whistle detection; time difference of arrival; underwater acoustic; underwater sound sensing; ocean sound measurement
