Patent ID: 6775388
Filing Date: 2004-08-10
Classification: B06B

Abstract:
A sonic transducer comprising:(a) a conductive membrane; (b) a backplate comprising at least one electrode; and (c) disposed between the membrane and the backplate, a dielectric spacer comprising a series of depressions arranged in a pattern, the depressions forming cavities each resonant at a predetermined frequency, wherein (d) the backplate comprises a plurality of electrodes and the depressions vary in depth through the spacer, depressions of different depths forming cavities resonant at different frequencies, different ones of the electrodes being aligned with depressions having a consistent depth; and (e) the depressions of varying depth facilitate wide operational bandwidth at least over ultrasound frequencies such that generation, by the membrane, of ultrasound modulated with an audio signal is demodulated as it passes through the atmosphere to thereby create a highly directional audible sound.