Characteristic resonance signatures for acoustical scattering from fish

摘要

Abstract: Scattering from fish is an important issue for biologists, aquaculturalists, and the military community. One can track the habits of fish, determine their abundance, and learn to distinguish them from targets of military interest by accurate mathematical formulations of the problem. The aim of this work is to present a mathematical/physical formulation by coupling acoustical signals with fish bladder properties to describe the acoustical scattering from fish bladders. In this work we first develop the theory to describe acoustical scattering from a viscous spherical shell filled with air; and then use it to show how the scattering amplitude and Q of the monopole resonance are modified by the viscosity and thickness of the shell. We then show how the theory may be extended, using a mathematical formulation based on coupled boundary integral equations, to account for the systematics of fish bladder scattering when elongation and viscous effects are combined. !17