A previous formula used for inferring speed of sound in marine organisms is considered and compared with the result from a wave scattering theory. Comparison indicates that there exists a difference between the two results, and the difference increases with the relative sound-speed contrast, and with the ratio between the dimension of animals and the acoustic wavelength. However, it is shown analytically that in the Rayleigh scattering regime and when the mass density difference between the target organisms and the medium is negligible that the earlier formula can be recovered by the result from the wave scattering theory, thereby providing a further physical and mathematical basis to the previous formula. (C) 1998 Acoustical Society of America.
