Simulation approach and causality evaluation for an active noise control system

An approach to simulate the performance of an active noise control system is proposed. The simulated result is shown to be a good approximation to that of a real system. By means of this approach some examples which may not be easily realisable in practical implementations are studied. Results concerning causality and filtered-x-type algorithms are interesting. Simulations show that the investigated active noise control system needs a considerable causality margin to perform well. This is explained by the inverse modelling nature of the selected feedforward controller. An example of the delayed inverse modelling of a nonminimum-phase system is given in which the quality of the inverse modelling depends on the delays