An ultrasonic emitter device for converting electrical signals to audio output by acoustic heterodyning of ultrasonic emissions. The device comprises a rigid core member having a top surface which includes an array of cavities of predetermined size and means for enhancement of at least one resonant frequency operable as a carrier frequency within an ultrasonic frequency range. An electrostatic field is generated at the top surface of the core member, and operates with respect to a resilient, dielectric diaphragm disposed in tension along the top surface and across the cavities to allow an intended range of orthogonal displacement of emitting sectors of the diaphragm positioned over the cavities and within a strong portion of the electrostatic field. A conductive medium is applied to one face of the diaphragm and is electrically isolated from the core member. A modulating circuit coupled to the conductive medium develops a variable electrostatic field to be applied to the diaphragm which interacts with the electrostatic field of the core member to develop a series of ultrasonic compression waves emanating from the emitting sectors of the diaphragm within the desired ultrasonic resonant frequency range and which propagate the series of ultrasonic compression waves which are demoduled within a nonlinear air medium to generate audio output.