A system and method for tissue differentiation. In the method, M acoustic signals si(t), i=1 to M, are obtained from M locations on a body surface. The N signals are subjected to band pass filtering using N band-pass filters, so as to generate NXM signals sij(t), i=1 to M, j=1 to N. K images I1 to IK, where K≦N, are then generated using the signals sij(t), i=1 to M, j=1 to N. The pixels are divided into a predetermined number L of categories Cl, l from 1 to L, using the images I1 to IK. For each category Cl, l from 1 to L, and for each pixel p(x,y), A probability pl of assigning the pixel p(x,y) to the category Cl is determined. An image may then be generated using the probabilities pl.