Adaptive feedforward multiple-input, multiple-output active noise control

The signal processing structure for an adaptive multiple-input, multiple output feedforward active acoustic noise control system is described. The controller contains two filter sections. The first section is a block of finite impulse response (FIR) filters that connects each input microphone to each loudspeaker output. The second section implements a matrix-infinite impulse response (IIR) structure. Each loudspeaker output influences its own and all other outputs through recursing filters. As a result, the algorithm can compensate for feedback that often exists due to acoustic paths from the loudspeaker outputs to the microphone inputs. An RLMS filtered-U update is described to adapt the controller to an unknown plant. Analysis of the simulated and experimental system shows that the ability to cancel noise at several points is partially determined by the linear independence of the loudspeaker/error paths