| There is a lot of noise in life that interferes with people's lives and work.The active noise canceling headphones become a reliable tool to cancel the noise by using active control to generate a signal with the same energy as the noise signal and the phase is reversed.(1)This article first uses the existing active noise canceling headphones in the market for test analysis.The test mainly uses artificial heads to simulate ergonomics,and uses standard microphones at the head and ears of the human head to read noise signals,and then uses dual-channel data.The collector collects the signal and compares the noise between the headphones without headphones,the headphones without noise reduction,and the headphones with noise reduct:ion to reduce the noise.The factors that affect the noise reduction performance are discussed separately,such as the noise incident angle and the noise decibel size.(2)Understand the LMS algorithm and analyze the performance of the algorithm.Including the algorithm convergence,convergence speed and computational complexity.Gives the theory of active noise reduction and lists noise reduction system structures(ie,feedforward active noise reduction,feedback active noise reduction,and hybrid active noise reduction systems),and analysis limitations on non-adaptive active noise reduction systems.Finally,the correlation of the LMS is applied to obtain the relationship between the convergence speed and the step size μ and the length of the control filter.(3)Based on the theoretical basis of FxLMS algorithm as the main guiding algorithm of feedforward active noise reduction,a feedforward active noise reduction headphone system based on DSP is built,which includes circuit construction and design,software environment setup and software program design.Finally,the actual test of the system,using single-frequency signals,multi-frequency signals and white noise as the main noise sources,respectively,to verify system noise reduction performance. |
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