International Symposium on Grids & Clouds 2017

2017/3/5-10 @ Academia Sinica, Taipei, Taiwan

Listening to the ecosystem: the integration of machine learning and a long-term soundscape monitoring network

Tzu-Hao Lin, Yu Tsao
Research Center for Information Technology Innovation, Academia Sinica

Yu-Huang Wang
Taiwan Biodiversity Information Facility, Biodiversity Research Center, Academia Sinica

Han-Wei Yen
Academia Sinica Grid Computing

Information on the variability of environment and biodiversity is essential for conservation management. In recent years, soundscape monitoring has been proposed as a new approach to assess the dynamics of biodiversity. Soundscape is the collection of biological sound, environmental sound, and anthropogenic noise, which provide us the essential information regarding the nature environment, behavior of calling animals, and human activities. The recent developments of recording networks facilitate the field surveys in remote forests and deep marine environments. However, analysis of big acoustic data is still a challenging task due to the lack of sufficient database to recognize various animal vocalizations. Therefore, we have developed three tools for analyzing and visualizing soundscape data: (1) long-term spectrogram viewer, (2) biological chorus detector, (3) soundscape event classifier. The long-term spectrogram viewer helps users to visualize weeks or months of recordings and evaluate the dynamics of soundscape. The biological chorus detector can automatically recognize the biological chorus without any sound template. We can separate the biological chorus and non-biological noise from a long-term spectrogram and unsupervised identify various biological events by using the soundscape event classifier. We have applied these tools on terrestrial and marine recordings collected in Taiwan to investigate the variability of environment and biodiversity. In the future, we will integrate these tools with the Asian Soundscape monitoring network. Through the open data of soundscape, we hope to provide ecological researcher and citizens an interactive platform to study the dynamics of ecosystem and the interactions among acoustic environment, biodiversity, and human activities.

5th Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan

2016/11/28-12/2 @ Honolulu, USA

Acoustic response of Indo-Pacific humpback dolphins to the variability of marine soundscape

Tzu-Hao Lin, Yu Tsao
Research Center for Information Technology Innovation, Academia Sinica

Shih-Hau Fang
Department of Electrical Engineering, Yuan Ze University

Chih-Kai Yang, Lien-Siang Chou
Institute of Ecology and Evolutionary Biology, National Taiwan University

Marine mammals can adjust their vocal behaviors when they encounter anthropogenic noise. The acoustic divergence among different populations has also been considered as the effect of ambient noise. The recent studies discover that the marine soundscape is highly dynamic; however, it remains unclear how marine mammals alter their vocal behaviors under various acoustic environments. In this study, autonomous sound recorders were deployed in western Taiwan waters between 2012 and 2015. Soundscape scenes were unsupervised classified according to acoustic features measured in each 5 min interval. Non-negative matrix factorization was used to separate different scenes and to inverse the temporal occurrence of each soundscape scene. Echolocation clicks and whistles of Indo-Pacific humpback dolphins, which represent the only marine mammal species occurred in the study area, were automatically detected and analyzed. The preliminary result indicates the soundscape scenes dominated by biological sounds are correlated with the acoustic detection rate of humpback dolphins. Besides, the dolphin whistles are much complex when the prey associated scene is prominent in the local soundscape. In the future, the soundscape information may be used to predict the occurrence and habitat use of marine mammals.

Ecoacoustics 2016

2016/6/5-8 @ University of Michigan

Investigation on the dynamics of soundscape by using unsupervised detection and classification algorithms

Tzu-Hao Lin, Lien-Siang Chou
Institute of Ecology and Evolutionary Biology, National Taiwan University, Repubic of China (Taiwan)

Yu-Huang Wang
Biodiversity Research Center, Academia Sinica, Repubic of China (Taiwan)

Soundscape has been proposed as a potential information source to study the variability of biodiversity. However, analysis of the soundscape is a challenging task when there is no sufficient database to recognize various sounds collected from long duration recordings. Previous researches have measured several acoustic diversity indexes to quantify the variation of biodiversity, but the acoustic diversity indexes are still difficult to interpret without any ground truth. In this study, we propose to analyze the composition of soundscape scenes and visualize the dynamics of soundscape by using unsupervised detection and classification algorithms. Different soundscape scenes were classified according to the tonal sounds, pulsed sounds, and acoustic features obtained from long-term spectrogram. By adjusting the variation explained through classification results, the number of soundscape scenes will be automatically determined. The unsupervised classifier has been employed to analyze the soundscape dynamics in several forests and shallow marine environments in Taiwan. Our results demonstrate that the seasonal and diurnal changing patterns of geophony, biophony, and anthrophony can be effectively investigated. Besides, the spatial change of soundscape can also be discriminated according to the composition of soundscape scenes. After the biophony scenes have been identified, we can apply the same classifier again to measure the complexity of biological sounds and examine the variability of biodiversity. The current approach provides researchers and managers a visualization platform to monitor the dynamics of soundscape and to study the interactions among acoustic environment, biodiversity, and human activities in the future.

2016年臺灣地球科學聯合學術研討會

2016/5/20

近海與海岸環境 Land-Ocean Interactions in the Changing Coastal Zones of Taiwan:
Scientific Basis and Societal Engagements

應用非監督式分類方法調查海洋聲景的時空變化

林子皓
國立台灣大學生態學與演化生物學研究所

海洋聲景由環境音、動物聲音與人為噪音所組成,是由各種水下聲音所構築而成的音響環境。環境音可能來自於風浪、海流、地震等等自然事件,受到海床地形、水文的變化,聲音在各地傳播的路徑有所不同,進而塑造出獨特的音響環境。動物音主要來自於海洋動物發聲,也可能來自動物移動過程或水面活動伴隨發出的聲音。動物音具有高度複雜的變異性,以鯨豚和魚類為例,不同種的聲音特徵有所差別,但同種的聲音卻也有可能受到行為影響而有著不同的結構。海域的人為噪音則以船隻交通、海洋工程的噪音為主,依據接受強度的不同,噪音可能會使動物受到生理傷害、干擾行為、遮蔽溝通,長期暴露下也可能增加免疫壓力。因此,調查海洋聲景不只可以協助我們了解海洋環境特性、海洋動物的種類組成與活動特性,更可以了解人為噪音對海洋生態的影響。近年來隨著水下技術的發展,國際上開始廣泛應用自動錄音機收集長時間水下錄音調查海洋聲景的時空變化。然而目前仍缺乏完整資料庫辨認各種聲音,也難以利用人工分析巨量錄音,因此阻礙了海洋聲景生態學的發展。本研究運用資訊分析技術,解析海洋聲景的事件組成,以進一步了解海洋環境與生態的動態變化。在野外取回水下錄音之後,計算每五分鐘水下錄音的平均功率頻譜,以壓縮大量的錄音資料,並將一系列的平均功率頻譜組合成長期時頻譜圖做為視覺化分析海洋聲景的基礎資料。此外,將每五分鐘的平均功率頻譜作為分析參數,經過多變數分析方法減少特徵向量的維度之後,利用區分資料在多重維度空間內的分佈叢集,作為非監督式分類海洋聲景事件的分析架構。本研究應用自行開發的演算法分析苗栗中港溪口附近海域的水下錄音資料,結果顯示海洋聲景的事件組成在以泥沙底質為主的河口海域以及礁石為主的人工魚礁附近有明顯的結構性差異。海洋聲景在河口海域以較為安靜的環境音、以及夜晚出現的石首魚群鳴唱為主,但在人工魚礁附近則是以吵雜的槍蝦聲音、以及傍晚過後出現的低頻魚群鳴音為主要的事件。透過視覺化分析海洋聲景事件組成的時序變化,將可協助海洋生態研究人員進一步了解各地的海洋動物群聚組成與生態系統的動態變化,並提供海洋生態保育經營的重要基礎資料。

Oceanoise Asia 2016

2016/4/20

Characterization of the marine soundscape at the core habitat of Indo-Pacific humpback dolphins

Tzu-Hao Lin, Lien-Siang Chou
Institute of Ecology and Evolutionary Biology, National Taiwan University

Shane Guan
Office of Protected Resources, National Marine Fisheries Service, Silver Spring, MD, USA

The soundscape in shallow waters displays a high level of spatial variation due to the difference in ocean environments, biological communities, and human activities. Many marine animals rely on sound for orientation; therefore, the soundscape has been hypothesized as one of the environmental indicators for marine animals. The population of Indo-Pacific humpback dolphins in western Taiwan waters is critically endangered. The anthropogenic noise might alter the marine soundscape evidently. However, the importance of soundscape for the habitat selection of cetacean remains unclear until now. In this study, underwater recorders were deployed in inshore waters to compare the difference of soundscape between the core habitat and non-core habitat of humpback dolphins. The result indicates that the composition of soundscape scene is different among our recording stations. At the core habitat, soundscape was characterized by the nighttime chorus of croakers and the quiet ambient sound in the daytime. On the contrary, snapping shrimp sounds represent the most dominated sound at the non-core habitats. The current result indicates that humpback dolphins prefer soundscape dominated by the chorus of their prey resources. The potential impacts of human activities on marine soundscape should be carefully evaluated in the future.

2016 動物行為暨生態研討會

2016/1/25-26

中華白海豚核心棲地的海洋聲景特徵以及保育經營的應用

林子皓、周蓮香

國立台灣大學生態學與演化生物學研究所

Shane Guan

美國國家海洋漁業局保護資源辦公室

海洋聲景由環境音、動物音以及人為噪音所組成,物理環境影響了聲音傳播,各地不同的動物群聚與人類活動也塑造出各種獨特的聲景。聲景中的訊息可讓海洋動物尋找適合的棲地,察知其他個體的活動位置,甚至探測獵物位置,因此可說是海洋動物生存的重要資源之一。台灣西部淺海的中華白海豚族群面臨許多威脅,水下噪音除了可能造成聽力損傷、行為干擾之外,也會改變當地的海洋聲景。但目前仍缺乏對白海豚棲地的聲景研究,也不清楚聲景的變化是否影響白海豚的棲地選擇。本研究於苗栗縣海域收集長時間水下聲音,分析時頻譜圖的時空變化,發現中港溪口的聲景與其他地區之間有明顯差異。中港溪口是中華白海豚的核心棲地,聲景以白天安靜的環境音和夜間吵雜的石首魚鳴唱為主。白海豚鮮少活動在龍鳳漁港外海的定置網區,以及外埔漁港外海的魚礁區,當地聲景則以槍蝦的寬頻脈衝聲與船隻噪音為主,石首魚的夜間鳴唱也較為低頻且不明顯。本研究結果顯示海洋聲景確實在白海豚核心與非核心棲地之間存在差異,高強度的石首魚鳴唱可能代表充足的食餌資源。未來除了可透過海洋聲景了解白海豚的潛在棲地,也可利用水下監聽站自動監測白海豚、石首魚與人為活動在各地海域的動態變化,以協助中華白海豚重要棲息環境的保育經營。

International Conference on Biodiversity, Ecology and Conservation of Marine Ecosystems 2015 @ Hong Kong

1-4 June 2015

Seasonal changes in habitat use of Indo-Pacific humpback dolphins at an estuary

Tzu-Hao Lin, Chia-Yun Lee, Lien-Siang Chou

Institute of Ecology and Evolutionary Biology, National Taiwan University

Tomonari Akamatsu

National Research Institute of Fisheries Engineering, Fisheries Research Agency

River estuaries are ecotone environments where freshwater and seawater mix together. Seasonal rainfall is likely to influence the salinity, turbidity, and development of estuarine fronts, thus alter the distribution of aquatic animals at an estuary. Indo-Pacific humpback dolphin is a coastal species that use estuaries as their core habitat. According to previous studies, the distribution of humpback dolphins in their estuarine habitat moved seaward during wet seasons. In addition, circling movement associated with the hunt for epipelagic fish increased during flooding tides. However, it remains unclear how seasonal rainfall influences the estuarine habitat use of humpback dolphins. During July 2009 and October 2014, acoustic data loggers were deployed at the Xin Huwei River estuary, Taiwan to record ultrasonic pulsed sounds. Biosonar clicks of humpback dolphins were detected using an automatic detection algorithm. The temporal variations of humpback dolphin behavior were investigated in terms of detection rate, occurrence pattern within the tidal cycle, echolocation behavior. The behavior of humpback dolphins significantly varied among the four monitoring sections and two periods (wet and dry seasons). The tide related occurrence was evident at the entire monitoring area during wet seasons, however, the similar occurrence pattern was only observed at the inner and outer estuary during dry seasons. In addition, long distance biosonars were much frequently detected at the inshore and offshore sections. During drought periods, the inshore and offshore sections are less likely to be influenced by the mixtures between freshwater and seawater. Our results suggest the river runoff may play an important factor in shaping the estuarine habitat use of humpback dolphins. Therefore, it is necessary to consider the interception of river runoff in the conservation management of humpback dolphins in an estuarine habitat.