A new robust narrowband active noise control system with online secondary-path modeling and frequency mismatch compensation

Narrowband active noise control (ANC, NANC) systems provide excellent performance in suppressing the annoying noise signals generated by rotating machines, which may be modeled as sinusoidal signals in additive noise. In real-world applications, two important issues including secondary path modeling (SPM) and frequency mismatch (FM), namely, the error of the nonacoustic timing signal sensor, need to be addressed by the NANC system in order to achieve sufficient noise reduction. In this paper, a new robust NANC system is proposed which contains three subsystems, namely: 1) an online secondary-path modeling subsystem designed to track the time-varying secondary path, 2) an FM compensation subsystem providing modified frequencies to every ANC channel, and 3) a cost reduction subsystem where only two x-filtering blocks are placed regardless of the number of the targeted frequencies. The three subsystems are seamlessly integrated such that the entire NANC system enjoys great advantages in both noise reduction and computational efficiency. Simulation results as well as application to real noise are conducted to demonstrate the effectiveness and capabilities as well as robustness of our proposed system.