The Use of Airborne Ultrasonics for Generating Audible Sound Beams

A device known as a parametric array employs the nonlinearity of the air to create audible sound from inaudible ultrasound, resulting in an extremely directive, beamlike wide-band acoustical source. This source can be projected about an area much like a spotlight, and creates an actual spatialized sound distant from the transducer. A basic theoretical analysis of the airborne parametric array is outlined and verified experimentally, and future challenges are discussed.