The Institute of Acoustics A B Wood Medal 2019: Julien Bonnel

Abstract

A common requirement in ocean acoustic applications is for robust signal processing algorithms that take into account the complex ocean environment, which is variable in space and time. Julien Bonnel's research has provided the most innovative approach to signal processing of broadband acoustic data in the last decade: time and frequency warping. Warping is a non-linear signal re-sampling method, based on a physical model of the shallow water sound channel, which compensates for dispersion in the propagating modes. The technique extracts the propagating modes from broadband signals in shallow water at significantly shorter ranges than previously possible, using data from only a single hydrophone. The technique he has developed has applications in two important areas: geo-acoustic inversion in shallow water environments and passive detection and localization of marine mammals. An example of the latter is the localization based on whale vocalizations, to enable estimation of the animal's depth in the water. The method has been successfully applied to obtaining the range and depth of bowhead whales in the Chuchki Sea and North Atlantic Right Whales in the Bay of Fundy. Julien continues his research in geo-acoustic inversion to develop methods for extracting modal wavenumbers from short horizontal arrays. Of significant general interest is his work on re-formulating the modal filtering technique for sound channels with different dispersion characteristics. Julien Bonnel is a most promising early-career research scientist who has introduced innovative methods that have led to significant advances in ocean acoustics. The research community has benefitted from the use of his methods and he has done this within a few years of completing his PhD. Importantly, he continues to produce innovative research to improve the methods that he has already developed. The IOA is delighted to present Julien Bonnel with the 2019 A B Wood Medal.