Patent ID: 8783411
Filing Date: 2014-07-22
Classification: B64D,G10K

Abstract:
1. A method comprising: using a frequency converter, converting at least a portion of acoustic energy in an unshifted acoustic signal emitted by an acoustic source in a first frequency range into acoustic energy in an upshifted acoustic signal in a second frequency range; and emitting at least a portion of the upshifted acoustic signal into an ambient acoustic environment, wherein: the second frequency range is higher than the first frequency range, and the unshifted acoustic signal comprises one or more unwanted acoustic noise signals; the frequency converter comprises two or more resonant members connected to the acoustic source and a coupling member connecting the resonant members together; each resonant member exhibits at least one corresponding acoustic resonance frequency in the first frequency range; each resonant member is connected to the acoustic source so that the unshifted acoustic signal drives each resonant member at its acoustic resonance frequency; the coupling member exhibits a nonlinear acoustic response so as to generate in the second frequency range sum-frequency acoustic signals from the resonant frequencies of the driven resonant members; and the upshifted acoustic signal includes the sum-frequency acoustic signals.