An Active Noise Cancelling Algorithm with Secondary Path Modeling

This paper presents a hybrid active noise canceling (HANC) algorithm to overcome the acoustic feedback present in most ANC system, together with an efficient secondary path estimation scheme. The HANC system provides a solution of two fundamental problems present in these kind of ANC systems: The first consists in a reduction of the acoustic feedback from the cancellation loudspeaker to the input microphone, using two FIR adaptive filters, one with a feedforward configuration an the other with a feedback adaptive filter configuration. To overcome the secondary path modeling problem, a modification of the method proposed by Akhtar is used. Computer simulation results are provide to show the noise cancellation and secondary path estimation performance of presented scheme. Key-Words.Active noise canceling, secondary path estimation, feed-forward ANC, feedback ANC, FxLMS, hybrid structure, Akhtar method.