Imagine broadcasting sound in a targeted and specific manner. Instead of using a bullhorn to speak to a crowd, you could single out one person in that crowd without disturbing anyone else. Or, picture a museum where displays "talk" right to you and leave other spectators in blissful silence.
American Technology Corp. can do all that and more. Its Hyper-Sonic Sound Technology (HSS) uses ultrasonic waves beyond the range of human hearing to shape audible sound waves and limit the areas where they can be heard to very narrow pathways. More specifically, normal sound moves through the air in small pressure waves. The air's nonlinear nature slightly changes the wave, producing new sounds. By knowing how the air will affect the sound, equipment can be used to send ultrasonic waves into the air with sufficient volume to create these new frequencies. Since ultrasonic waves are inaudible, they can limit the sound in question to a specific area.
HSS sound systems consist of an audio program source like a CD player or microphone, an HSS signal processor, and an ultrasonic emitter or transducer powered by an ultrasonic amplifier. The signal processor converts the sound, such as music or a voice, to a complex ultrasonic signal. The transducer then amplifies it and emits it into the air. The ultrasonic energy's directional nature forms a virtual column of sound directly in front of the emitter, much like light from a flashlight. To hear the sound, listeners must have their ears in line with the column.
For details, see www.atcsd.com.