Frequency‐domain active noise control system using optimal step sizes

Abstract

AbstractIn this paper, a new frequency‐domain active noise control (ANC) system is proposed in which an optimal step size is used for updating at each frequency. The proposed system achieves convergence faster than in the case of the conventional ANC system with the Filtered‐x LMS method updated with the step size converging at the fastest speed. This is because the step size with the fastest convergence can be adapted at each frequency in the proposed system. In the conventional system, convergence is not possible unless the phase error of the secondary path model satisfies the stability condition. In the proposed system, on the other hand, excellent silencing characteristics without divergence can be obtained by letting the step size become 0 at frequencies not satisfying the stability condition, because a different step size at each frequency can be used. In this paper, the theoretical equation for the optimal step size is derived by using only the information obtainable during system operation. Next, a configuration of the ANC system that can make use of the optimal step size derived from this theoretical equation is explained. Further, the method for identifying the frequency causing instability and its control method are explained. Finally, by computer simulation, the effectiveness of the proposed system is verified. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(7): 51–61, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10000