Modified-filtered-x LMS algorithm based active noise control systems with improved online secondary-path modeling

This paper proposes a new method for active noise control systems with online secondary-path modeling. The main features of the proposed method are that the modified-FxLMS (MFxLMS) algorithm is used in adapting the noise control filter and a new variable step-size (VSS) LMS algorithm is used in the secondary-path modeling filter. The step-size is varied in accordance with the power of the residual error signal (the desired response for the modeling filter). It is found that the desired response for the modeling filter is corrupted by a noise which is decreasing in nature, (ideally) converging to zero. Hence, a small step-size is used initially and later its value is increased accordingly. Computer simulations show that the proposed method gives better performance than the existing methods.