The Suppression Of Spike Noise Of Anti-noise Caused By Physical Noise

Noise pollution is one of the world’s environmental problems. Currently, there are two methods to control noise pollution. One is called the passive noise control, which commonly used in high-frequency noise control but to low-frequency noise control is poor. The other one is called the active noise control, which make up for the lack of the passive noise control. In recent years, the research on the theory of active noise control has been mature, mainly focuses on the control algorithm. But its practical application research has been slow. Based on the result of the researchers and the practical application of the active noise control, this paper find that the physical noise can cause spike noise of anti-noise. It’s one of factors in interference effect of active noise control. And the present literature researching on this problem is not much. This paper has avoided the large space and time inconsistency problem, and found in a small spatial scale, the sound is spread on a plane. Under these assumed conditions, this paper conducts the research to the suppression method of the spike noise of anti-noise, which caused by physical noise. The main research contents are as follow:①This paper introduces the characteristics, hazards and control methods of noise pollution, and explained the significance of active noise control, and its research status, control theory as well as the problems of its existence. And points out the physical noise causing spike noise of anti-noise is one of factors in interference effect of active noise control.②According to the problem of spike noise of anti-noise which caused by physical noise, based on a single channel adaptive active noise control model, this paper establishes active noise control model and gives simulation to anti-noise which extracted from the model using by Matlab.③This paper describes the principle of LMS adaptive filtering as well as wavelet analysis theory, and compares the inhibitory effect of the LMS adaptive filtering method and the wavelet threshold method on spike noise of anti-noise. Through the comparison of these two methods, this paper draws the conclusion that the inhibitory effect of the wavelet threshold method on spike noise of anti-noise is better than the inhibitory effect of the LMS adaptive method, and its anti-noise output has higher SNR, better smoothness, and more suitable than the LMS adaptive filtering method in practice, because it does not require desired signal. This paper compares the inhibitory effect of the wavelet threshold at different decomposition layers on spike noise of anti-noise, obtained that layer decomposition adaptive wavelet threshold is a good way to inhibit spike noise of anti-noise which caused by physical noise.④This paper puts up a simple physical hardware experiment, which verified layer decomposition adaptive wavelet threshold has a good effectiveness for suppressing spike noise of anti-noise caused by physical noise.