ACTIVE NOISE-CONTROL USING A DUAL FEEDFORWARD APPROACH

A dual feedforward controller for active noise control is presented. T he first part of the controller is designed to cancel broadband noise, and the second part is an adaptive controller designed to cancel peri odic noise. A simple technique to identify the parameters of the broad band controller is developed. An autoregressive moving-average model i s used, and it is found that its stability is improved by prefiltering the test signal with a minimum-phase inverse of the secondary noise c hannel. The periodic controller uses an estimate of the fundamental fr equency to cancel the first few harmonics of periodic noise. A computa tionally efficient adaptive technique based on least squares is develo ped to update the harmonic controller gains at each time step. Experim ental results are included which demonstrate simultaneous cancellation of both random broadband noise and periodic noise.