Speaker: Julien Bonnel - Associate Scientist at Woods Hole Oceanographic Institution

https://mit.zoom.us/j/96617226852

Abstract: Lobsters, whales and submarines have little in common. Except that they produce low-frequency sounds, like many other marine occupants that use sound for communication, foraging, navigation and other purposes. However, unraveling and using the underwater cacophony is not at all simple. This is particularly true for low-frequency (f<500 Hz) propagation in coastal water (water depth D<200 m), because the environment acts as a dispersive waveguide: the acoustic field is described by a set of modes that propagate with frequency-dependent speeds. In this context, to extract relevant information from acoustic recording, one needs to understand the propagation and to use physics-based processing. In this presentation, we will show how to analyze low-frequency data recorded on a single hydrophone. We will notably review modal propagation and time-frequency analysis. We will then show how those can be combined into a non-linear signal processing method dedicated to extract modal information from single receiver, and how such information can be used to localize sound sources and/or characterize the oceanic environment. The whole method will be illustrated on several experimental examples, including geoacoustic inversion on the New England Mud Patch and baleen whale localization in the Arctic. 

Bio: Julien Bonnel received his Ph.D. degree in signal processing from Grenoble Institut National Polytechnique, Grenoble, France, in 2010. From 2010 to 2017, he was an Assistant/Associate Professor with Laboratoire des Sciences et Technologies de l’Information, de la Communication et de la Connaissance (Lab-STICC, UMR CNRS 6285), Ecole Nationale Superieure de Techniques Avancees de Bretagne, ENSTA Bretagne, Brest, France. Since September 2017, he has been an Associate Scientist with Woods Hole Oceanographic Institution, Woods Hole, MA, USA, where he received tenure in September 2020. His research in signal processing and underwater acoustics includes time–frequency analysis, source detection/localization, geoacoustic inversion, acoustical tomography, passive acoustic monitoring, and bioacoustics. Dr. Bonnel is the recipient of the 2019 A.B. Wood Medal from the Institute of Acoustics (U.K.) and the 2020 R. Bruce Lindsay Award from the Acoustical Society of America (USA).