Multirate Audio-Integrated Feedback Active Noise Control Systems Using Decimated-Band Adaptive Filters for Reducing Narrowband Noises

Abstract

Audio-integrated feedback active noise control (AFANC) systems deliver wideband audio signals and cancel low frequency narrowband noises simultaneously. The conventional AFANC system uses single-rate processing with fullband adaptive active noise control (ANC) filter for generating anti-noise signal and fullband audio cancelation filter for audio-interference cancelation. The conventional system requires a high sampling rate for audio processing. Thus, the fullband adaptive filters require long filter lengths, resulting in high computational complexity and impracticality in real-time system. This paper proposes a multirate AFANC system using decimated-band adaptive filters (DAFs) to decrease the required filter lengths. The decimated-band adaptive ANC filter is updated by the proposed decimated filtered-X least mean square (FXLMS) algorithm, and the decimated-band audio cancelation filter can be obtained by the proposed on-line and off-line decimated secondary-path modeling algorithms. The computational complexity can be decreased significantly in the proposed AFANC system with good enough noise reduction and fast convergence speed, which were verified in the analysis and computer simulations. The proposed AFANC system was implemented for an active headrest system, and the real-time performances were tested in real-time experiments.

Dynamic Matching of Reconstruction and Anti-Aliasing Filters in Adaptive Active Noise Control

“…However, this method requires a determined model to design the reconstruction filter and anti-aliasing filter under the assumption that the spectral structure of the primary sound source is known. As audio processing in ANC systems is an important application and the basic requirement of the sampling rate for audio processing is higher than that for active noise control, a multi-rate system has also been used to balance the computational complexity and functional requirements [25]. As field-programmable gate array (FPGA) processors develop, their better parallel calculation properties can significantly enhance the calculation speed; therefore, some researchers have tried to use FPGAs for room noise control [26] and head-mounted feedforward ANC systems [27].…”