Two presentations at ASA Victoria Meeting

Applying machine-learning based source separation techniques in the analysis of marine soundscapes

Tzu-Hao Lin1, Tomonari Akamatsu2, Yu Tsao3, Katsunori Fujikura1

1Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology
2National Research Institute of Fisheries Science, Japan Fisheries Research and Education Agency
3 Research Center for Information Technology Innovation, Academia Sinica

Long-term monitoring of underwater soundscapes provides us a large number of acoustic recordings to study a marine ecosystem. Characteristics of a marine ecosystem, such as the habitat quality, composition of marine fauna, and the level of human interference, may be analyzed using information relevant to environmental sound, biological sound, and anthropogenic sound. Supervised source separation techniques have been widely employed in speech and music separation tasks, but it may not be practical for the analysis of marine soundscapes due to the lack of a database that includes a large mount of paired pure and mixed signals. Even when the paired data is not available, different sound sources with unique spectral or temporal patterns may still be separated by apply semi-supervised or unsupervised learning algorithms. In this presentation, supervised and unsupervised source separation techniques will be demonstrated on long-term spectrograms of a marine soundscape. Separation performances under different levels of simultaneous source influence will also be discussed. In the future, more advanced techniques of source separation are necessary to facilitate the soundscape-based marine ecosystem sensing. An open database of marine soundscape will promote the development of machine learning-based source separation. Therefore, we will open acoustic data tested in this presentation on the Asian Soundscape to encourage the open science of marine soundscape.

Information retrieval from a soundscape by using blind source separation and clustering

Tzu-Hao Lin1, Yu Tsao2, Tomonari Akamatsu3, Mao-Ning Tuanmu4, Katsunori Fujikura1

1Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology
2Research Center for Information Technology Innovation, Academia Sinica
3National Research Institute of Fisheries Science, Japan Fisheries Research and Education Agency
4Biodiversity Research Center, Academia Sinica

Passive acoustic monitoring represents one of the remote sensing platforms of biodiversity. However, it remains challenging to retrieve meaningful biological information from a large amount of soundscape data when a comprehensive recognition database is not available. To overcome this issue, it is necessary to investigate the basic structure of a soundscape and subsequently retrieve biological information. The recent development of machine learning-based blind source separation techniques allow us to separate biological choruses and non-biological sounds appearing on a long-term spectrogram. After the blind source separation, the temporal-spatial changes of bioacoustic activities can be efficiently investigated by using a clustering algorithm. In this presentation, we will demonstrate the information retrieval in the forest and marine soundscapes. The separation result shows that in addition to biological information, we can also extract information relevant to weather patterns and human activities. Furthermore, the clustering result can be used to establish an audio library of nature soundscapes, which may facilitate the investigation of interactions among wildlife, climate change, and human development. In the future, the soundscape-based ecosystem monitoring will be feasible if we can integrate the soundscape information retrieval in a large-scale soundscape monitoring network.

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Listening to the deep: Exploring marine soundscape variability by information retrieval techniques

Presentation in the session of Lidar and Passive observing sensors, Oceans’18 Kobe

Listening to the deep: Exploring marine soundscape variability by information retrieval techniques

Tzu-Hao Lin1, Yu Tsao2

1Department of Marine Biodiversity Research, Japan Agency of Marine-Earth Science and Technology, Yokosuka, Japan
2Research Center for Information Technology Innovation, Academia Sinica, Taipei, Taiwan

Information on the dynamics of the deep-sea ecosystem is essential for conservation management. The marine soundscape has been considered as an acoustical sensing
platform to investigate geophysical events, marine biodiversity, and human activities. However, analysis of the marine soundscape remains difficult because of the influence of simultaneous sound sources. In this study, we integrated machine learning-based information retrieval techniques to analyze the variability of the marine soundscape off northeastern Taiwan. A long-term spectral average was employed to visualize the longduration recordings of the Marine Cable Hosted Observatory (MACHO). Biotic and abiotic soundscape components were separated by applying periodicity-coded nonnegative matrix factorization. Finally, various acoustic events were identified
using k-means clustering. Our results show that the MACHO recordings of June 2012 contain multiple sound sources. Cetacean vocalizations, an unidentified biological chorus, environmental noise, and system noise can be accurately separated without an audio recognition database. Cetacean vocalizations were primarily detected at night, which is consistent with the detection results of two rule-based detectors. The unidentified biological chorus, ranging between 2 and 3 kHz, was primarily recorded between 7 p.m. and midnight during the studied period. On the basis of source separation, more acoustic events can be identified in the clustering result. The proposed
information retrieval techniques effectively reduce the difficulty in the analysis of marine soundscape. The unsupervised approach of source separation and clustering can improve the investigation regarding the temporal behavior and spectral characteristics of different sound sources. Based on the findings in the present study, we believe that variability of the deep-sea ecosystem can be efficiently investigated by combining the
soundscape information retrieval techniques and cabled hydrophone networks in the future.

2017年動物行為生態研討會

2017/1/23-24 @ 高雄中山大學

應用機器學習探討海洋聲景變動與中華白海豚發聲活動之關聯

林子皓、曹昱
中央研究院資訊科技創新研究中心

方士豪
元智大學電機工程學系

鯨豚的發聲行為相當多變,不同族群可能會在各種環境音改變哨聲特徵﹐也會在遭遇人為噪音時改變聲音結構。海洋聲景是由環境音、動物音與人為噪音組成,具有高度變異的特性。儘管過去已有不少針對鯨豚發聲與單一音源的研究,但是對鯨豚如何在多變的海洋聲景且多重聲源相互重疊的狀況下改變行為仍不清楚。本研究透過水下錄音機,長期收錄2014年苗栗海域的海洋錄音。首先應用自動偵測器尋找中華白海豚水下聲音,再應用非負矩陣分解法學習海洋聲景中的主要聲源特徵。透過非監督式學習器,可以有效拆解長期時頻譜圖,視覺化呈現石首魚鳴唱、槍蝦聲音、環境與人為噪音等主要聲源的相對變化。利用廣義疊加模型分析聲景與白海豚聲音後,我們發現白海豚的聲音偵測率與複雜度和各種聲源皆有不同的相關性。此結果顯示應用機器學習分離聲景中的各種聲源之後,將能夠有效瞭解動物和各種聲源的交互作用。未來,聲景中的各種訊息也可以作為預測動物活動的生態遙測資料。

2015台灣聲學學會第28屆學術研討會

2015/11/13

從海洋聲景探討中華白海豚的棲地特徵

 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

淺海聲景受到各地地理環境、生態群聚以及人為活動的影響而具有高度的變異性。許多海洋動物仰賴聲音訊息尋找活動方位,因此聲景可能是海洋動物棲地環境的指標之一。中華白海豚在台灣西岸的族群量少於80隻,主要使用3-15 kHz的哨聲溝通,並使用超音波的生物聲納進行回聲定位,因此聲音的感知對牠們相當重要。然而,目前仍不了解聲景是否在中華白海豚的棲地選擇中扮演重要的角色。本研究於苗栗海域利用SM2+錄音機長期收錄水下聲音,自動偵測回聲定位聲音,以了解中華白海豚的核心活動區域。長期時頻譜分析顯示,苗栗海域的聲景有明顯的日週期變化,且可在中華白海豚核心棲地與非核心棲地之間觀察到不同的頻譜特徵。核心棲地的中、高頻聲壓標準差較大,但平均值較低。顯示核心棲地的聲景特徵,以夜間的石首魚群體鳴唱,和白天較低的環境音為主。非核心棲地則有截然不同的聲景特徵,石首魚群體鳴唱較不明顯,但可偵測到大量槍蝦的寬頻脈衝聲波。未來許多離岸風力發電廠的開發工程將在西岸進行,本研究可協助相關單位了解中華白海豚棲地的海洋聲景變化。

關鍵字:中華白海豚、海洋聲景、生物音、時空變化、聲音偵測器

The soundscape in shallow marine environment displays a high level of spatial variation due to the regional change of geophysical environment, biological community, and human activity. Many marine animals rely on sounds for orientation; therefore the soundscape has been hypothesized as one of the environmental indicators. Indo-Pacific humpback dolphins in western Taiwan waters are critically endangered. The sound perception is essential for humpback dolphins, which communicate through 3-15 kHz whistles and echolocate through ultrasonic clicks. However, the importance of soundscape for their habitat selection remains unclear. In this study, SM2+ recorders were deployed in Miaoli waters to collect long-duration underwater recordings. Echolocation clicks were automatically detected to identify the core habitat of humpback dolphins. The long-term spectral average reveals that the soundscape in Miaoli waters evidently changed among the diurnal cycle. The spectral characteristic varied between the core habitat and non-core habitat. The soundscape at the core habitat was characterized by the higher standard deviations and lower means of SPL in mid- and high-frequency range. It indicates that the nighttime chorus of croakers and the low-level of ambient sound in the daytime represent the classical soundscape at the core habitat. On the contrary, the croaker chorus was less prominent at the non-core habitat. Instead, snapping shrimp sounds dominated the local soundscape. The current results can help understand the soundscape change of humpback dolphin habitat during the future development and operation of offshore wind farms.

Keywords:Sousa chinensis, marine soundscape, biological sound, temporal and spatial variations, sound detector

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