This paper demonstrates a strategy for rapid estimation of particle size distributions based on wide-band ultrasound attenuation measurement in solid/liquid suspensions. The excess attenuation due to the presence of particle is first measured as a function of frequency, in a suspension of known particle mass fraction. A model of this attenuation that incorporates the dependency of ultrasound frequency, particle mass fraction, and particle size distribution is then required. An algorithm is then presented that estimates the parameters of the underlying model, thus obtaining an estimate of the particle size distribution. The algorithm is evaluated with numerical simulations as well as measurement on suspensions of Dolomite particles. The results show that the estimated particle size distribution agrees with what is to be expected from the mechanical sieving used in preparation of the samples.