Research And Application Of Multi-channel Active Noise Control Fast Algorithm

Noise is a kind of pollution that exists widely in daily life,and it has a negative impact on human health.For example,noise pollution can damage people's auditory system.Therefore,reducing noise pollution is a research topic of great significance.The active noise control system is a real-time system.It mainly uses an adaptive filter to track the noise signal,and then plays a “anti-noise” to coherently cancel the original noise.Most of the researches in active noise control field focus on how to improve the performance of algorithms,but the improvement always accompany with increasing of computational complexity.It brings difficulties to implement active noise control system.And most of the research that implement the active noise control system use the least mean square(LMS)algorithm and its improved algorithms.This algorithm is easy to implement with small computations,but the performance is poor.Therefore,this paper adopts the affine projection algorithm which has faster convergence rate and smaller steady-state error,instead of LMS algorithm to achieve better performance in multi-channel active noise control system.However,the computational complexity of this algorithm is huge,so this paper focus on the fast affine projection algorithm,and present a simple structure which has a lower degree of coupling with the adaptive filter order,in the same time,proposed algorithm can reduce computational burden and has better noise reduction performance than the LMS algorithm.This paper combines three existing high-efficiency calculation strategies in affine projection algorithm(APA),which greatly reduces the computational complexity and reduces the coupling degree between adaptive filter length and computational complexity.Then the algorithm structure of the affine projection algorithm applied in the field of active noise control is optimized,which further reduces the calculation amount and reduces the coupling degree between the secondary path modeling filter length and the calculation amount.The optimized algorithm keeps the convergence performance of the algorithm while reducing the amount of computation.The ultimate goal of this paper is to implement an active noise control system,and actually verify the effect of the optimized algorithm.Therefore,in this paper the most basic algorithm,filtered-x least mean square(FxLMS)algorithm,in the field of active noise control is firstly analyzed.Based on FxLMS algorithm and DSP chip a hardware platform is builded,and a audio preprocessing circuit is designed for the abrupt noise with impulse characteristics,which makes it smooth when the amplitude of the noise signal increases suddenly,and improves the stability of the system.To get a better reduction effect,the FxLMS algorithm has been substituted with APA in this paper and the performance of muti-channel active noise control has been verfied with recorded actual vehicle interior noise in a hardware platform which enclosed in a confined space.