Research On Active Noise Reduction Technology In Enclosed Space

In recent years,as people pay more and more attention to environmental protection and healthy life,their tolerance for noise pollution is getting lower and lower.Closed spaces such as indoors,cars,and cabins are important places for people’s production and life.There is an increasing demand for noise reduction in these enclosed environments.In the daily noise spectrum,low-frequency noise accounts for a large proportion and is difficult to effectively control.Traditional passive noise reduction technology is difficult to solve low-frequency noise problems.Active noise reduction technology may become an effective means to solve low-frequency noise problems.Therefore,this thesis adopts the method of Active Noise Control(ANC)to solve the noise problem in the closed space,and combines the practical application to complete the overall scheme design and algorithm performance optimization of the ANC system to achieve effective control of noise.In this thesis,the feasibility of active noise reduction is first verified based on the principle of sound wave interference,and the adaptive filter and LMS algorithm are applied to the active noise reduction system by combining the theory of active noise reduction and the principle of adaptive control.Aiming at the problem of mutual constraints between the stability and convergence speed of the FxLMS algorithm,a leakage variable step size FxLMS adaptive filtering algorithm is proposed based on the normalized function and the exponential function to improve the real-time performance of the algorithm.After simulation analysis,the algorithm shows faster convergence speed and lower steady-state misalignment.In addition,in order to solve the problem of limited noise reduction range of the single-channel ANC system,this thesis designs a dual-channel active noise reduction system by obtaining the secondary channel model through offline modeling.Through Matlab simulation,when the input signal is a mixed frequency random signal,the superiority of the double-pass improved algorithm over the FxLMS algorithm in noise reduction performance is compared and analyzed.To verify the actual noise reduction effect of this system on low-frequency noise,the hardware structure design and software programming of the dual-channel active noise reduction system were completed,and a DSP-based dual-channel experimental platform was designed and built.and a closed three-dimensional space measuring 6m ×3.5m ×3m was selected as the experimental environment,and the noise reduction effect was analyzed by drawing the distribution map of the sound pressure value in the three-dimensional space.The results show that in a certain frequency and area,the active noise reduction system can effectively reduce the noise in the closed space and achieve a good noise reduction effect,which provides a certain technical reference for the future three-dimensional space active noise reduction technology.It has practical significance to improve people’s quality of life.