Spatial Active Noise Reduction System Near The Human Ear

With the progress of the times and the development of society,noise has a profound impact on people's life and work.The long-term regional noise will cause permanent damage to the human body and its hearing system,so the research of regional noise reduction system becomes more and more important.People usually use ear band passive materials for sound absorption or noise reduction earphones.Although they can achieve certain noise reduction effect,wearing them for a long time will cause ear discomfort.Therefore,it is necessary to discuss the technology of producing static region in the space near human ear,and to form a static region near the human ear by reducing the noise of the error microphone.(1)The least mean square algorithm is studied and analyzed.The performance of the algorithm is mainly analyzed,including convergence conditions,convergence speed and computational complexity.On this basis,the noise reduction effect and system limitations of adaptive feedforward,feedback active noise control algorithm and traditional feedforward and feedback hybrid control algorithm are analyzed and compared.Aiming at the coupling effect of traditional combination method,two new combination methods are studied for decoupling.(2)It is found that the location of secondary sound source,error sensor and noise source affects the regional noise reduction performance under different sound field characteristics such as mode and diffusion.This paper focuses on the influence of secondary sound source and error sensor location on the noise reduction effect of the system.In the anechoic room,the regional noise reduction experiment near the human ear is carried out for designing the circuit,building the experimental environment and testing the system.The main algorithm is feedforward feedback hybrid control active noise reduction.Two kinds of secondary sound source layout schemes are designed,and the noise reduction effects of feedforward,feedback and hybrid control under different schemes are compared to verify the optimal noise reduction performance of the system.(3)The experiment needs multi-channel measurement,which requires the synchronous acquisition and analysis of a variety of characteristic parameters of the signal.In this paper,we choose the appropriate hardware architecture,with the help of the powerful computing and processing ability of the computer,combined with the design idea of Lab VIEW and virtual instrument,in order to reduce the development cycle and cost of the system,and improve the scalability and flexibility of the system,to develop a low delay,high synchronous audio signal acquisition and analysis system.