A hybrid active noise cancelling with secondary path modeling

This paper presents a hybrid active noise cancelling (ANC) system, to overcome the acoustic feedback present in most feedforward ANC system, together with an on line secondary path estimation scheme. The ANC system provides a suitable solution to two important problems present in most ANC systems. The acoustic feedback is reduced using two FIR adaptive filters with feedforward and feedback configurations, respectively; while the secondary path modeling is carried out using a modification of the on line estimation method proposed by Akhtar. Computer simulation results show that the combination of the feedback and feedforward stages provides a fairly good acoustic feedback cancellation, while the secondary path estimation method performs fairly well, providing both a fairly good noise cancellation performance.