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Multi-channel ANC system using optimized reference microphones based on time difference of arrival

Feedforward active noise control (ANC) system using upstream reference signal can reduce various noises such as broadband noise by arranging a reference microphone close to a noise source. However, the performance of ANC system deteriorates if the noise environment such as the arrival direction is changed. This is because of the causality constraint that the unwanted noise propagates to the control point faster than the "antinoise" to cancel the unwanted noise. To solve this problem, we propose an ANC system that estimates the arrival direction of noise using multiple reference microphones placed around the control point. This system uses a time difference of arrival technique to estimate noise source location and then optimize reference signal. Noise reduction performances are examined through some simulations in this paper.