Scientific Article

Contribution of bone-reverberated waves to sound localization of dolphins: A numerical model

¹ Sorbonne Université, CNRS-INSU, Institut des Sciences de la Terre Paris, ISTeP UMR 7193, 75005 Paris, France
² Sorbonne Université, Laboratoire d’Imagerie Biomédicale (LIB),CNRS 7371 – INSERM 1146, 75006 Paris, France
³ UMR 7179 C.N.R.S/M.N.H.N., Bâtiment d’Anatomie Comparée, 75005 Paris, France
⁴ Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King’s College London, WC2R 2LS London, UK
⁵ Department of Zoology, University of Oxford, OX1 2JD Oxford, UK
⁶ Dipartimento di Geoscienze, Università degli Studi di Padova, 35122 Padova, Italy
⁷ INGV Istituto Nazionale di Geofisica e Vulcanologia, Via Donato Creti, 12, 40100 Bologna, Italy

^* Corresponding author: aida.hejazi_nooghabi@upmc.fr

Received: 5 May 2020
Accepted: 2 December 2020

Abstract

We implement a new algorithm to model acoustic wave propagation through and around a dolphin skull, using the k-Wave software package [1]. The equation of motion is integrated numerically in a complex three-dimensional structure via a pseudospectral scheme which, importantly, accounts for lateral heterogeneities in the mechanical properties of bone. Modeling wave propagation in the skull of dolphins contributes to our understanding of how their sound localization and echolocation mechanisms work. Dolphins are known to be highly effective at localizing sound sources; in particular, they have been shown to be equally sensitive to changes in the elevation and azimuth of the sound source, while other studied species, e.g. humans, are much more sensitive to the latter than to the former. A laboratory experiment conducted by our team on a dry skull [2] has shown that sound reverberated in bones could possibly play an important role in enhancing localization accuracy, and it has been speculated that the dolphin sound localization system could somehow rely on the analysis of this information. We employ our new numerical model to simulate the response of the same skull used by [2] to sound sources at a wide and dense set of locations on the vertical plane. This work is the first step towards the implementation of a new tool for modeling source (echo)location in dolphins; in future work, this will allow us to effectively explore a wide variety of emitted signals and anatomical features.