A novel active noise control system with online secondary-path filter based on a stepsize controller

In active noise control (ANC) systems, it is important to estimate the control filter and the secondary-path filter simultaneously since the secondary path can be changed by changing the position of the loudspeaker in real time. However, it is very difficult to estimate two unknown filters at the same time since the estimation errors of the two filters can affect the each estimation. In this paper, a stepsize controller was proposed to improve the convergence stability and noise reduction ability. The stepsize controller assumes that the errors in the estimation of the secondary path are large measurement noises in terms of estimation of the control filter and adjusts the stepsize of the control filter until the measurement noises are reduced. It can provide the stable ANC systems since the estimation of the control filter is automatically controlled according to the estimation of the secondary-path filter. The proposed ANC system was also applied to the scheduled-stepsize algorithm [1]. The simulation results show stable estimations of the filters and improved noises reduction levels.