Design Of Noise Barrier With Acoustic Diffusers Top Structure And Analysis Of Noise Reduction Performance

With the rapid development of modern society,more and more traffic bring about many traffic noise which seriously endangered people's normal work and life also seriously affect people's health.As one of the main measures to prevent and control the road traffic noise pollution,the noise barriers have been widely used at home and abroad.The traditional sound barriers have a significant effect on the high frequency noise,and the effect on the low frequency noise is not obvious.In order to increase the noise reduction effect of the sound barriers on the middle and low frequency noise,and improve the overall noise reduction performance of the sound barriers,the paper adopts the method of applying the Schroeder diffusers to the top of the acoustic barriers,and combining diffusion theory calculation,acoustic finite element analysis and acoustic experiment test to study the noise reduction characteristics of noise barriers.In this paper,based on the analysis of the acoustic principle of the sound barriers,the mechanism of transmission,reflection and diffraction are discussed.And the common types of noise barriers are introduced.The paper also analyze the structure of Schroeder diffusers and the calculation method of diffusion and diffusion theory.Based on the Fourier transform of acoustic wave,theoretical calculations of plates and various Schroeder diffusers are carried out,and the acoustic scattering characteristics of the diffusers are analyzed.Compared with the flat structure,the diffusers structure exhibits significant acoustic diffusivity.In the acoustic analysis software,the sound barrier model of different top structure forms are created.AML acoustic finite element analysis method are used to simulate the noise barrier insertion loss and analysis of noise characteristics.The influence of the sequence of the diffuser structure,the design frequency,the order and the slot width on the noise reduction performance of the noise barrier are studied.Comparing with the common sound barrier of the same height,the noise barrier with the top structure of the diffuser has significant noise reduction effect in the middle and low frequency.The experimental study on sound barriers with the diffuser top structure are carried out in a semi anechoic chamber.The effect of noise reduction on the vertical structure sound barrier is studied.The additional sound attenuation after adding various peaks are calculated,and the noise reduction performance of the diffusion type noise barrier and the law of changing with the parameters are verified.Top structure with application value of Sound barriers are obtained.The absorption / diffusion composite structure is studied.The sound barriers with acoustic diffuser and absorption material composite structure are tested.The parameters about the sound absorption properties of micro perforated plates are calculated.Thedesign parameters of composite structure of micro perforated plate and diffuser are determined,and the sound pressure curve of composite top structure sound barrier are tested.The composite structure of the diffuser and the micro perforated plate has the function of diffusion and sound absorption,and the noise reduction effect of the noise barrier has been further improved,to meet the engineering requirements.