Real-time remote cancellation of multi-tones in an extended acoustic cavity using directional ultrasonic loudspeaker

This paper presents an adaptive active noise control (ANC) method to remotely cancel multi-tone noise signals in a room using ultrasonic `AudioSpotLight´ (ASL) as the noise canceling loudspeaker. The ASL is a directional parametric array loudspeaker whose 60 kHz carrier frequency is modulated by the anti-noise signal generated by adaptive ANC algorithm. The proposed method uses no secondary path estimate and is capable of canceling the tonal noise signals at distant target points, in real time. Using adaptive Leaky-NLMS algorithm, noise attenuation levels (NAL) of up to 15.71 dB are obtained in the presence of diffused low frequency background noise. Performance analysis of the proposed system is presented and the results of a simple real-time implementation are also provided to support the proposed ANC method.