Design And Implementation Of Indoor Noise Reduction System Based On FPGA

Noise pollution has become the second major environmental factor affecting human health after air pollution.It not only affects the human nervous system,but also causes heart disease,digestive diseases,tinnitus and deafness.In recent years,people's research on noise elimination technology mainly focuses on noise canceling headphones,aircraft cabins,cars,etc.There are few researches on noise elimination in indoor space,mostly for theoretical analysis and not for engineering applications.Combines acoustic simulation and electronic technology,this thesis designs an indoor low-frequency noise active control system based on the principle of acoustic interference to improve the indoor sound field environment.The system generates an anti-noise signal of the same frequency as the noise source through the speaker,and implements noise suppression in the control point region based on the principle of acoustic interference.The main accomplishments of this thesis are:First,analyze the main noise sources in the room,use the recorder to collect specific noise,perform spectrum analysis in MATLAB,and determine the noise type and characteristics.Second,combine with the theory of acoustic analysis,the acoustic simulation tool is used to simulate the specific indoor space.The finite element analysis method and the multi-point deployment method are used to solve the optimal position of the secondary source,which provides a theoretical basis for the placement of the secondary speakers in the actual noise reduction system.Third,the structure and control principle of the active noise reduction system are studied,and the LMS algorithm is used to implement the adaptive filter.The algorithm is modeled and simulated by MATLAB,and the influence of the convergence speed and stability of the algorithm on the noise reduction performance of the system is studied.Fourth,the design of the multi-channel audio signal acquisition module is completed,and the operation processing of the audio signal and the circuit implementation of the active noise control system are completed based on the FPGA.Fifth,use the established indoor low-frequency noise active control system,the active noise reduction experiments were carried out on the single-frequency noise signal and the indoor specific noise signal.The experimental results show that the designed system reduces the noise of the specific frequency by about 13 dB and the actual noise generated by the indoor household appliances by about 8dB in the specific area.The experiment proves that the system has certain practical value for improving indoor noise.