Separating underwater ambient noise from flow noise recorded on stereo acoustic tags attached to marine mammals

• Published in: Journal of Experimental Biology
• Main Authors: von Benda-Beckmann, Alexander M., Wensveen, Paul Jacobus, Samarra, Filipa I. P., Beerens, S. Peter, Miller, Patrick J. O.
• Other Authors: Office of Naval Research, University of St Andrews. School of Biology, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Institute of Behavioural and Neural Sciences, University of St Andrews. Centre for Social Learning & Cognitive Evolution, University of St Andrews. Bioacoustics group
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: DTAG; Megaptera novaeangliae; Orcinus orca; QH301 Biology; Ecology; Evolution; Behavior and Systematics; Physiology; Medicine(all); Aquatic Science; Animal Science and Zoology; Molecular Biology; Insect Science; SDG 14 - Life Below Water; QH301; Humpback Whale; Orca
• Online Access: https://hdl.handle.net/10023/10867; https://doi.org/10.1242/jeb.133116

A.M.v.B.B. and P.B. were funded by The Netherlands Ministry of Defence. Fieldwork efforts and support for P.M. and F.S. was provided by the US Office of Naval Research [award numbers N00014-08-1-0984 and N00014-10-1-0355]. P.W. received a PhD studentship with matched funding from The Netherlands Ministry of Defence (administered by The Netherlands Organisation for Applied Scientific Research, TNO) and UK Natural Environment Research Council [NE/J500276/1]. Sound-recording acoustic tags attached to marine animals are commonly used in behavioural studies. Measuring ambient noise is of interest to efforts to understand responses of marine mammals to anthropogenic underwater sound, or to assess their communication space. Noise of water flowing around the tag reflects the speed of the animal, but hinders ambient noise measurement. Here, we describe a correlation-based method for stereo acoustic tags to separate the relative contributions of flow and ambient noise. The uncorrelated part of the noise measured in digital acoustic recording tag (DTAG) recordings related well to swim speed of a humpback whale (Megaptera novaeangliae), thus providing a robust measure of flow noise over a wide frequency bandwidth. By removing measurements affected by flow noise, consistent ambient noise estimates were made for two killer whales (Orcinus orca) with DTAGs attached simultaneously. The method is applicable to any multi-channel acoustic tag, enabling application to a wide range of marine species. Peer reviewed