Hybrid active noise control system for correlated and uncorrelated noise sources

A feedforward active noise control (ANC) system requires a reference signal correlated with the primary disturbance. In situations when such correlated reference signal cannot be obtained, a feedback type ANC may be employed. A hybrid ANC system is combination of feedforward and feedback control, where objective is to simultaneously control both the correlated and uncorrelated primary disturbances. In this paper, we identify problems with the conventional hybrid ANC systems, and propose an improved performance hybrid ANC system. The proposed method introduces third adaptive filter to the conventional hybrid ANC system. The objective is to generate appropriate error and reference signals for feedforward and feedback ANC filters. Computer simulations are carried out which demonstrate that the proposed method can effectively mitigate the correlated and uncorrelated primary disturbances appearing at the error microphone.