the inventive acoustic filter comprises two solid bodies , at least one of which is piezoelectric . said bodies are interconnected in such a way as to form a plane interface between them , acoustic waves being generated by the piezoelectric body by means of an electrical field and being guided by the plane interface between the two solid bodies . the solid bodies are selected wish the objective of ensuring that the acoustic energy of said waves decreases exponentially in the two bodies in a perpendicular direction to the interface , starting from the interface .