Berry effect in acoustical polarization transport in phononic crystals

We derive the semiclassical equations of motion of a transverse acoustical wave packet propagating in a phononic crystal, subject to slowly varying perturbations. The formalism gives rise to Berry effect terms in the equations of motion, manifested as the Rytov polarization rotation law and the polarization-dependent Hall effect. We show that the formalism is also applicable to the case of non-periodic inhomogeneous media, yielding explicit expressions for the Berry effect terms.