A Hybrid Active Noise Cancellation Algorithm for Suppressing Narrowband Noise with Rapidly Changing Frequencies

This study presents a novel hybrid active noise cancellation algorithm designed to enhance the convergence speed and achieve the noise reduction required for narrowband noise, particularly under conditions of rapidly changing noise frequencies. The proposed hybrid algorithm improves upon a previous hybrid algorithm by incorporating an additional feedforward path with an adaptive notch filter. The previous hybrid algorithm utilised a supporting filter to separate the error signal into correlated and uncorrelated components for processing in the feedforward and feedback structures. However, it exhibited limitations in controlling narrowband noise with rapidly changing frequencies due to issues such as the time delay caused by the convergence speed and improper separation of the error signal. By integrating the adaptive notch filter, the proposed hybrid algorithm addresses these limitations. To evaluate its convergence speed and noise reduction performance, the proposed algorithm was first validated through computer simulations and then implemented in a real passenger car for real-time control experiments aimed at attenuating narrowband C2 engine order noise. Results from both computer simulations and real-time experiments demonstrated that the proposed hybrid algorithm outperformed the previous hybrid algorithm, particularly in terms of the convergence speed and noise reduction performance under rapidly changing noise frequencies.