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A multi-tone active noise control system with a simplified local on-line secondary-path modeling.

Multi-tone active noise control (multi-tone ANC) technology has been widely studied to reduce the tonal noise with low frequencies. In the case of an ANC system with a time-varying secondary path, an on-line modeling method is necessary. In this work, a multi-tone ANC system with a simplified local on-line secondary-path modeling method is presented. A two-tone signal with small amplitude is added at the sideband of each noise tone to conduct the local modeling. The least mean square algorithm is used as the modeling algorithm which provides tracking for a time-varying secondary path. Notch filters and bandpass filters are adopted to separate the primary tones and the additive tones. Simulations and experimental results show that the proposed algorithm has good performance.