Based on a fully Galilean electrodynamics of dielectric deformable bodies, a completely deductive derivation of the coupled, dynamical, electromagnetic, electroacoustic, and energetic equations and constitutive equations for elastic, pyroelectric, ferroelectric dielectrics accommodating viscosity and dielectric‐relaxation phenomena is presented. Of necessity the theory is first constructed in a fully nonlinear framework even though applications to signal processing are envisaged. Then a linearization is performed by Lagrangian variation about an initial ferroelectric state in which there exist no strains, but there are present both stresses and local electric field as well as an initial electric polarization. The latter provokes a breaking of the ideal symmetry of the material, so that finally linearized coupled electroacoustic and heat‐propagation equations are deduced on which can be based the study of coupled acoustic‐soft optic modes in ferroelectrics of the BaTiO3‐type. No thermodynamical restriction other than the fulfillment of the second principle of thermodynamics is considered, so that dissipative processes such as viscosity and dielectric relaxation appear naturally on an equal footing with elasticity, piezoelectricity, thermoelasticity, and pyroelectricity.