In the present paper we investigate the conditions of plane waves' propagation in cubic crystals subject to initial deformations and electric fields. The analysis is extended to all symmetry classes belonging to the cubic system, exhibiting, or not, the piezoelectric effect. We show the influence of the electrostrictive and piezoelectric effects on wave propagation in such media. We derive the velocities of propagation as closed-form solutions, and we analyze the influence of the initial fields on the waves polarization in two main cases: (i) propagation along a cube edge; (ii) propagation along a cube face. In the second case we define a generalized anisotropy factor and we show the influence of the initial fields on it and on the shape of slowness surfaces.