A hybrid ANC system with a sinusoidal noise canceller equipped with a variable step-size LMS algorithm

摘要

If the primary and reference noise signals contain not only wideband but also narrowbandcomponents, the conventional broadband active noise control (BANC) and narrowbandANC (NANC) systems may lose their noise reduction merits. Recently, a hybrid ANCsystem has been proposed to tackle this problem, where a sinusoidal noise canceller (SNC)is introduced to improve the noise environment for the BANC subsystem that follows toperform effectively. The SNC uses an LMS algorithm that has a fixed step size or avariable one of deterministic nature. However, the SNC works inadequately when the noiseenvironment is nonstationary. In this paper, the LMS algorithm used in the SNC isreplaced by one with variable step sizes that are of stochastic nature and change accordingto both the SNC error and the reference signals. This variable step-size LMS based SNCenjoys improved estimation and tracking capabilities as compared to its previous version.The only sacrifice to make is a little increase of implementation cost. Extensive simulationsfor numerous scenarios are conducted to confirm the effectiveness of the modified hybridANC system.