A phase-compensated distorted wave Born approximation representation of the bistatic scattering by weakly scattering objects: Application to zooplankton

The distorted wave Born approximation (DWBA) method has been successfully u sed in modeling the acoustic backscattering by weakly scattering zooplankto n [Stanton et al., J. Acoust. Sec. Am. 94, 3463-3472 (1993), Wiebe ct at, I EEE J. Ocean. Eng. 22(3), 445-464 (1997)]. However, the previously develope d DWBA model ignores the imaginary part of the scattering amplitude and thu s results in a zero-extinction cross section. As a consequence, the model f ails to predict the scattering-induced attenuation which could be important under certain circumstances. In this paper, a phase-compensated DWBA-based approximation is presented. The improved method allows us to compute not o nly the scattering strength but also the acoustic attenuation. The new scat tering model is validated by comparing with the existing exact solution for certain representative finite objects. The results from this study can be applied to bioacoustic applications where the attenuation due to scattering and/or multiple scattering by zooplankton is relevant, and where this info rmation might be used to infer the acoustic properties of live animals. (C) 1999 Acoustical Society of America. [S0001-4966(99)00410-5].