Varying auxiliary-noise-power for improved noise reduction in active noise control systems with online secondary path modeling

Abstract

Active noise control (ANC) systems with online secondary path modeling (SPM) comprise two adaptive filters: 1) The FXLMS algorithm-based ANC filter to cancel the primary noise, and 2) an LMS algorithm-based online SPM filter. The online SPM filter is a supporting filter and is needed for a stable operation of the FXLMS algorithm-based ANC filter. The online SPM is achieved by injecting an auxiliary noise, which however degrades the noise reduction performance of the ANC system. In this paper, a new method is proposed for varying the power of the injected auxiliary noise in accordance with the convergence status of the power of the error signal of the SPM filter. Furthermore, in order to deal with the non-stationary noise sources, normalized step-sizes are employed for both the ANC and SPM filters. The proposed method for varying the auxiliary-noise-power achieves a good online SPM, and an improved noise reduction performance as compared with the existing methods. Furthermore, it has a reduced computational complexity as compared with the method proposed by Carini et. al. In order to verify the effectiveness of the proposed method, various scenarios of the input noise are considered in the simulation results presented in this paper.