Feedforward noise cancellation in an airduct using generalized FIR filter estimation

A feedforward control algorithm for active noise control based on the recursive estimation of a generalized finite impulse response (FIR) filter is presented in this paper. The feedforward control algorithm is applied to a commercial air ventilation silencer to provide active noise compensation in an airduct. A generalized FIR filter has the same linear parameter structure as a taped delay FIR filter that is favorable for (recursive) estimation purposes. However, the advantage of the generalized FIR filters lies in the possibility to include prior knowledge of system dynamics in the tapped delay line of the filter. By comparison with a conventional FIR filter implementation it is shown that a significant improvement in noise cancellation is obtained.