Research On Railway Sound Barrier With Built-in Conch Sound Absorber

According to the noise distribution outside the train when the high-speed train is running,extracting the frequency spectrum variation of the noise source outside the train,and designing the metamaterial soundabsorbing unit and sound barrier suitable for the high-speed train is of great significance to improve the quality of life of the residents around the line.In order to meet the various low-frequency noise control and control requirements generated by today’s high-speed trains,a new type of conchlike cavity sound absorber was constructed based on the multi-stage resonance structure of the conch cavity.Using the methods of theoretical analysis,impedance tube test and finite element simulation,the acoustic performance of the conch-like cavity sound absorber is studied.The analysis results show that the conch-like sound absorber has excellent sound absorption performance at medium and low frequencies,the first sound absorption peak can reach more than 0.99,and it can have multiple high-order peaks in the frequency domain of 1000-3500 Hz,which can achieve more than 68.7% of the sound absorption.Broadband multi-stage sound absorption has great potential in practical applications of suppressing multi-source and low-frequency noise.Starting from the variation law of the noise source with speed and the vertical distribution characteristics during the operation of a high-speed train in a test,based on the experimental test and numerical simulation,an acoustic analysis model of the noise source and measuring points outside the high-speed railway was established,and the built-in conch-type sound absorption was analyzed.The law of the insertion loss of the sound barrier of the device is clear,and the requirements of the acoustic design are clarified.The influence law of the noise barrier material,geometric design,installation point and other factors on the noise reduction effect is explored.Through the acoustic boundary element simulation,it can be found that the overall sound transmission loss of the sound barrier in the frequency range of 0～3000Hz is significantly greater than that of the existing general sound barrier.,has the greatest impact on the sound field in the high-frequency cut-off area,and the maximum noise reduction can reach 22 d B,which can effectively prevent the sound pollution of the surrounding high-rise buildings during the operation of the high-speed railway.