Research Of Indoor Active Noise Reduction System And Experiment

Production and living noise,such as construction,honking of vehicle driving and square dancing,is easy to cause people to produce negative emotions such as irritability and anxiety,which seriously affects the rest and sleep of modern people.It causes the work state of the next day to be affected by light,heavy will cause cardiocerebrovascular and neurasthenia problems.It has a huge negative effect on the orderly progress of production and life.Noise control can be divided into passive noise control and active noise control.However,the passive noise reduction technology only has obvious effect on the control of high frequency noise and has the defect of poor control on the control of low frequency noise.Active noise control just makes up for its shortcomings,so the research of active noise control is very important.However,due to the randomness of indoor noise,traditional noise reduction methods cannot achieve good results.In order to better reduce low-frequency broadband noise,this paper carried out a study on the control of indoor random noise.The main research work and innovation points completed are as follows:(1)Two parameters,filter length and iteration step length,which determine the performance of the adaptive noise reduction system have the biggest impact on adaptive algorithms.This article from the basic principle of active noise control,introduces the basic theory of LMS algorithm based on Fir filter,and the simulation analysis of filter length,influence coefficients update iteration step on the active noise reduction system,convergence speed balancing system,performance stability and noise reduction effect.(2)A new improved algorithm is proposed to reduce the noise of the controller system so that the iteration step varies with the power of the input signal.Based on the single-channel system,different controller algorithms are analyzed according to the actual problems,such as Fxlms algorithm considering the secondary path transfer function,variable length Pfxlms iterative algorithm,consider the secondary source of acoustic feedback Fulms algorithm asked.And through theoretical analysis and simulation software based on Labview&Matlab comparison,verified the improved algorithm performance of active noise reduction system improved.Through theoretical analysis,the control principle of multi-channel algorithm is expounded.Theoretically,the more the number of active noise reduction channels,the better the theoretical noise reduction effect is.However,due to the high requirements of the controller algorithm stability and hardware equipment,the number of channels cannot be too much.(3)A rule of secondary loudspeaker layout in three-dimensional closed space is proposed.It is concluded that the secondary loudspeaker layout in active noise reduction system has great influence on the system.The research shows that the active noise reduction system has a great influence on the secondary loudspeaker cloth system,sound field of software Virtual.lab&Hyperworks three-dimensional closed space response characteristics and the secondary source position and strategy based on the effects of active noise control system secondary source system on the noise reduction effect.(4)Based on the proposed improved algorithm,an active noise reduction system platform combining simulation and experiment was established,which broke through the dilemma of no noise reduction effect of indoor random noise.this paper realizes Labview development platform for the realization of the secondary path transfer function of offline modeling and active noise control system based on the test of single frequency noise sources including narrowband noise and broadband noise,the test results show that the feasibility of active noise reduction system.