Time Domain Spherical Harmonic Analysis for Adaptive Noise Cancellation over a Spatial Region

Active Noise Cancellation (ANC) is a well researched topic for minimizing unwanted acoustic noise, and spatial ANC is a recently introduced concept that focuses on continuous spatial regions. Adaptive filter designing for spatial ANC is often based on frequency-domain spherical harmonic decomposition method, which has a major limitation due to the increased system latency. In this paper, we develop a time-domain spherical harmonic based signal decomposition method and use it to develop two time-space domain feed-forward adaptive filters for spatial ANC. Through simulations we show that the proposed methods can achieve higher noise reduction performance over the control region with microphones located on the surface of the region compared to the conventional time-domain adaptive filter.