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  • Acoustical Society of America (ASA)  (4)
  • 1
    Online Resource
    Online Resource
    Passive acoustic monitoring reveals year-round marine mammal community composition off Tasiilaq, Southeast Greenland
    Acoustical Society of America (ASA) ; 2022
    In:  The Journal of the Acoustical Society of America Vol. 151, No. 2 ( 2022-02-01), p. 1380-1392
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 151, No. 2 ( 2022-02-01), p. 1380-1392
    Abstract: Climate-driven changes are affecting sea ice conditions off Tasiilaq, Southeast Greenland, with implications for marine mammal distributions. Knowledge about marine mammal presence, biodiversity, and community composition is key to effective conservation and management but is lacking, especially during winter months. Seasonal patterns of acoustic marine mammal presence were investigated relative to sea ice concentration at two recording sites between 2014 and 2018, with one (65.6°N, 37.4°W) or three years (65.5°N, 38.0°W) of passive acoustic recordings. Seven marine mammal species were recorded. Bearded seals were acoustically dominant during winter and spring, whereas sperm, humpback, and fin whales dominated during the sea ice-free summer and autumn. Narwhals, bowhead, and killer whales were recorded only rarely. Song-fragments of humpback whales and acoustic presence of fin whales in winter suggest mating-associated behavior taking place in the area. Ambient noise levels in 1/3-octave level bands (20, 63, 125, 500, 1000, and 4000 Hz), ranged between 75.6 to 105 dB re 1 μPa. This study provides multi-year insights into the coastal marine mammal community composition off Southeast Greenland and suggests that the Tasiilaq area provides suitable habitat for various marine mammal species year-round.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/10.0009429
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2022
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    On the reliability of acoustic annotations and automatic detections of Antarctic blue whale calls under different acoustic conditions
    Acoustical Society of America (ASA) ; 2018
    In:  The Journal of the Acoustical Society of America Vol. 144, No. 2 ( 2018-08-01), p. 740-754
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 144, No. 2 ( 2018-08-01), p. 740-754
    Abstract: Evaluation of the performance of computer-based algorithms to automatically detect mammalian vocalizations often relies on comparisons between detector outputs and a reference data set, generally obtained by manual annotation of acoustic recordings. To explore the reproducibility of these annotations, inter- and intra-analyst variability in manually annotated Antarctic blue whale (ABW) Z-calls are investigated by two analysts in acoustic data from two ocean basins representing different scenarios in terms of call abundance and background noise. Manual annotations exhibit strong inter- and intra-analyst variability, with less than 50% agreement between analysts. This variability is mainly caused by the difficulty of reliably and reproducibly distinguishing single calls in an ABW chorus made of overlaying distant calls. Furthermore, the performance of two automated detectors, based on spectrogram correlation or subspace-detection strategy, is evaluated by comparing detector output to a “conservative” manually annotated reference data set, which comprises only analysts' matching events. This study highlights the need for a standardized approach for human annotations and automatic detections, including a quantitative description of their performance, to improve the comparability of acoustic data, which is particularly relevant in the context of collaborative approaches in collecting and analyzing large passive acoustic data sets.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.5049803
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2018
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Variability in ground-truth data sets and the performance of two automated detectors for Antarctic blue whale calls in different soundscape conditions
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 141, No. 5_Supplement ( 2017-05-01), p. 3604-3605
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 141, No. 5_Supplement ( 2017-05-01), p. 3604-3605
    Abstract: Automated detectors are important tools for processing large passive acoustic databases. Assessing the performance of a given method can be challenging and needs to be interpreted in the light of the overall purpose of analysis. Performance evaluation often involves comparison between the detector output and a ground-truth data set, which often involves manual analyses of the data. Such analyses may be subjective depending on, e.g., interfering background noise conditions. In this study, we investigated the variability between two analysts in the detection of Antarctic blue whale Z-calls (Balaenoptera musculus intermedia), as well as the intra-analyst variability, in order to understand how this variability impacts the creation of a ground-truth and the assessment of detector performances. Analyses were conducted on two test datasets reflecting two basins and different situations of call abundance and background noise conditions. Using a ground-truth based on combined results of both analysts, we evaluated the performances of two automated detectors, one using spectrogram correlation and the other using a subspace-detection strategy. This evaluation allows understanding how recording sites, vocal activity, and interfering sounds affect the detector performances and highlights the advantages and limitations of each of the methods, and the possible solutions to overcome the main limitations.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4987713
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Effects of subsampling of passive acoustic recordings on acoustic metrics
    Acoustical Society of America (ASA) ; 2015
    In:  The Journal of the Acoustical Society of America Vol. 138, No. 1 ( 2015-07-01), p. 267-278
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 138, No. 1 ( 2015-07-01), p. 267-278
    Abstract: Passive acoustic monitoring is an important tool in marine mammal studies. However, logistics and finances frequently constrain the number and servicing schedules of acoustic recorders, requiring a trade-off between deployment periods and sampling continuity, i.e., the implementation of a subsampling scheme. Optimizing such schemes to each project's specific research questions is desirable. This study investigates the impact of subsampling on the accuracy of two common metrics, acoustic presence and call rate, for different vocalization patterns (regimes) of baleen whales: (1) variable vocal activity, (2) vocalizations organized in song bouts, and (3) vocal activity with diel patterns. To this end, above metrics are compared for continuous and subsampled data subject to different sampling strategies, covering duty cycles between 50% and 2%. The results show that a reduction of the duty cycle impacts negatively on the accuracy of both acoustic presence and call rate estimates. For a given duty cycle, frequent short listening periods improve accuracy of daily acoustic presence estimates over few long listening periods. Overall, subsampling effects are most pronounced for low and/or temporally clustered vocal activity. These findings illustrate the importance of informed decisions when applying subsampling strategies to passive acoustic recordings or analyses for a given target species.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4922703
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2015
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
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