The distorted wave Born approximation (DWBA) method has been successfully used in modeling the acoustic backscattering by weakly scattering zooplankton [Stanton et al., J. Acoust. Sec. Am. 94, 3463-3472 (1993), Wiebe ct at, IEEE J. Ocean. Eng. 22(3), 445-464 (1997)]. However, the previously developed DWBA model ignores the imaginary part of the scattering amplitude and thus results in a zero-extinction cross section. As a consequence, the model fails 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 only the scattering strength but also the acoustic attenuation. The new scattering 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 information might be used to infer the acoustic properties of live animals. (C) 1999 Acoustical Society of America. [S0001-4966(99)00410-5].
