Multi-channel hybrid active noise control system for turboprop aircraft cabin

To address the challenging issue of hybrid broadband-narrowband noise suppression in turboprop aircraft cabins, this study proposes a novel multi-channel hybrid structured Active Noise Control (ANC) method. In the system architecture design, the feedforward structure employs an improved narrowband Filtered-x Least Mean Square (FxLMS) algorithm, which simplifies linear convolution operations into equivalent additive-multiplicative computations based on the characteristics of multi-frequency sinusoidal reference signals, significantly reducing computational complexity. The feedback structure adopts a partial update FxLMS algorithm with dynamic selection mechanism, effectively enhancing system convergence speed and stability through real-time optimization of filter update methods. Furthermore, a Residual Error Separation (RES) module and an alternating update method based on noise smoothing power are introduced to optimize computational resource allocation while ensuring noise reduction performance. Theoretical analysis indicates that the proposed hybrid system possesses extremely low computational complexity, and that the RES module effectively enhances the algorithm's convergence performance and stability by improving the condition number of the feedback system's autocorrelation matrix and reducing the instantaneous variance of the feedforward system's gradient estimate. Simulation and experimental results demonstrate that the constructed 1×2×2 multi-channel control system achieves effective total sound pressure level attenuation of 18.33 dB and 21.27 dB, verifying its effectiveness and engineering potential.