Development Of Noise-Reduction Module Based On Laser Detection

Noise pollution,water pollution and air pollution are the three major global pollution.Noise pollution can be divided into high-frequency noise and low-frequency noise pollution,compared to high-frequency noise,because the damage of low-frequecy noise pollution needs a relatively long time to show up,the harm is often overlooked by people,in fact,the low-frequency part of noise will be harmful to human body and sound environment,so people should pay more attention to low-frequency noise pollution and it's of great significance to take measures to control the noise pollution.The ways of noise reduction can be divided into passive noise-reduction and active noise-reduction,passive noise-reduction has a good effect to the high-frequency noise,but the effect to low-frequency noise is not satisfactory,if we still use passive noise reduction to control the low-ferquency noise,we need to design more structures to occupy more space,so this way will be restricted.Active noise-reduction system mainly contains the microphone,the speaker and the control circuit of noise signal processing,active noise-reduction system dosen't required lots of space,and there's very good effect of noise reduction to the low-frequency noise,so in terms of cost or effect,using method of active noise control is more appropriate for low-frequency noise.Based on the principle of active reduction and the principle of laser acoustics,the acoustic noise reduction module is manufactured,the loudspeaker array and other structures which are related to noise reduction are designed and fabricated.The active noise reduction system is built and we carry out the experiment of noise reduction of frequency noise signal,the main contents of this paper are as follows:First,carry out the system design of active noise-reduction module and analyze related requirements of system which is based on the principle of active noise-reduction.Considering the stability of the structure and the convenience of the installation,we complete active noise-reduction module in the frequency range of 0.5-1kHz.Second,research on sound system.Based on the principle of laser acoustic sensing,the noise source is collected and compaerd with frequency response of microphone when collecting the noise source.Third,carry out the control system research,the signal processing unit will achieve the following functions: the noise reference signal which is collected by the feedforward sound system will carry out the phase reverse processing;provide secondary sound source power amplifier signal.Fourth,secondary sound source system research,taking into account the speaker quality,price and other factors,choose cost-effective speaker,design secondary sound source,and carry out the research of the sound field of secondary sound source.Fifth,design and machining the structure of active noise-reduction module,and set up experimental system of noise reduction to complete the function test of noisereduction module.