Performance Analysis of Active Noise Control Over a Spatial Region

Active noise control (ANC) over region(s), or spatial ANC, extends the noise control from one or more points to the entire region(s). This paper proposes an evaluation method to predict the ‘noise reduction performance over the entire region’ (NRR) for any given spatial ANC system. This method formulates the acoustic potential energy of the residual signals over the region into spherical/cylindrical-harmonics coefficients (also named as ’wave-domain coefficients’), and further decomposes it into three components related to the coherence between reference signals at the reference microphones and primary signals over the region, filter coefficients, and an uncontrollable term due to physical and practical constraints. This analytical tool provides insight into the contribution of each component to the overall noise reduction performance over the entire region.