Research On Active Noise Feedforward Control System

Noise pollution almost exists in every scene of daily life,which seriously affects the efficiency of daily life and work.Noise can not only cause damage to hearing,but also induce many serious diseases.People’s auditory system,central nervous system,digestive system,immune system and visual organs will have irreversible damage in varying degrees.The common passive noise reduction method is to block the transmission of sound by isolation or absorption.The frequency of low frequency noise is very low and its diffraction ability is strong,so the passive noise reduction is usually effective only in the middle and high frequency segments.Active Noise Control(ANC)is a new noise reduction technology combining acoustic,digital signal processing and adaptive filtering technology,which has good control effect for low frequency noise.This technology has many advantages,such as good adaptive ability,excellent dynamic tracing ability,low steady-state error,low cost,simple equipment and small volume.Active noise reduction headset,ear and other related products have begun to enter the market,its good noise reduction experience has been widely recognized,active noise reduction technology has become a hot research topic in recent years.This paper introduces the adaptive filtering algorithm,control system structure,secondary channel and other key technologies in active noise reduction system,and conducts in-depth research on each part,and builds an active noise reduction system for simulation and experiment.In view of the contradiction between the steady-state error and the convergence speed of linear adaptive filtering algorithm,based on the variable step size algorithm,we introduce the function relation between iteration number and iteration step size in the updating formula of filter weight,and propose an improved VSS-NLMS algorithm.Through simulation analysis and comparison with the original variable step algorithm,it has lower steady-state error and faster convergence speed,improves the tracking ability of the system to the noise signal,and enhances the adaptability and stability of the system.We design an active noise reduction system based on Leaky Fx-LMS algorithm for the actual noise in real life.The Leaky-LMS algorithm in the loss function is introduced in the penalty on the filter coefficients,the algorithm for the primary noise is too large primary noise changes violently in the secondary source because the output power overload produce nonlinear distortion caused by the system with the divergence problem of the control effect of the.In the loss function,the parameters that adjust the proportion of penalty terms are adjusted in practical applications according to the stability of the system and the steady state error.Through the analysis and research of feedforward,feedback and multi channel,single channel array control structure,comparing the advantages and applicability of the scene,to build a system of active noise control,simulation and experiment of low-frequency broadband and narrowband low-frequency noise in real life,to verify its effectiveness.