Comparison of effective medium and multiple-scattering theories of predicting the ultrasonic properties of dispersions

Analytical expressions of the effective density and compressibility of a scattering medium derived using multiple-scattering theory (MST) and effective medium theory (EMT), assuming no R dependence, are compared. The EMT and MST are shown to be equivalent in the long wavelength limit. Differences between the ultrasonic velocity and attenuation predicted by the two theories, observed by earlier workers, can be attributed to the fact that simplified expressions for the scattering coefficient An were used in the EMT.