Abstract
A theory of the sound attenuation and dispersion in superfluid He3 is presented, which consistently takes into account three types of absorption mechanisms: (1) quasiparticle collisions, (2) pair breaking, and (3) excitation of collective modes of the order parameter. Results for the B phase, assuming it to be in the quasi-isotropic (Balian-Werthamer) state, are in good agreement with experiment.