Measurements of ultrasonic velocity and attenuation on a suspension of
sub-millimetre polystyrene spheres in a solution of aqueous sodium ch
loride were carried out over a frequency range of 4-12 MHz, for solid
volume fractions varying between 0 and 0.5. A method of predicting the
volume fraction at which the single scattering approximation becomes
unphysical due to multiple scattering has been proposed for these meas
urements. A comparison of the experimental data with the theoretical p
redictions of single scattering and two multiple scattering approaches
has been made. Good agreement was obtained between the experimental a
nd theoretical approaches, the predictions of the iterative multiple s
cattering model most closely approximating the experimental results.