ADAPTIVE FEEDFORWARD ACTIVE NOISE CONTROL MULTIPLE-INPUT, MULTIPLE-OUTPUT

The signal processing structure for an adaptive multipleinput, multiple-output feedforward active acoustic noise control system is described in this paper. The new controller contains two filter sections. The first section is a block of FIR fdters that connects each input microphone to each loudspeaker output. The second section implements a matrix-IIR structure. Each loudspeaker output influences its own and all other outputs through recursive fdters. 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 fdted-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.