Multichannel active noise control algorithms using inverse filters

In this paper, a simple inverse structure for multichannel active noise control (ANC) is introduced. This structure, combined with adaptive FIR filters and filtered-x LMS-based algorithms, can produce both a reduction of the computational load and an increase of the convergence speed, compared to the standard multichannel filtered-x LMS algorithm or its fast exact realizations. The proposed structure is based on the use of delayed non-causal models of the inverse plant between some error sensors (typically microphones in ANC systems) and some actuators (typically loudspeakers). Simulations using models of a realistic acoustic plant and inverse plant were performed, and the convergence gain that can be achieved with the proposed structure was demonstrated, while reducing the computational load of the control algorithm.