This paper presents the results of an experimental study of how an electric field affects the position of the plane of polarization of a transverse elastic wave and the acoustooptical interaction in the LiTaO3 crystal. It is established that an electric field of ±1×106 V/m rotates the plane of polarization of a sound wave with frequency 580 MHz passing through 1 cm of a crystal by 2.5 degree. The variation of the resonance frequency of piezoelectric cavities subjected to a constant electric field is also demonstrated with longitudinal vibrations in La3Ga5SiO14 crystal rods at temperatures between –60 and 80°C. For a field of ±1,5×10 6 V/m and α = 15°, the relative change of the frequency is ±120×10 –6. It is shown that La3Ga5SiO14 crystals offer a set of physical parameters that makes them promising for electrically controlled and nonlinear acoustoelectronic devices.