Acoustical attachments using the helmholtz resonators for railway noise barriers

초록

: This study is primarily aimed at developing a measure to overcome the limited shielding performance of noise barriers for high-speed trains. For 300km/h and faster trains, the noise, incidence angles and the height changes due to the pronounced aerodynamic noise source parts located at the middle and high positions differ when compared to conventional rolling noises. By means of experimental analysis of the sound radiation characteristics and the sound pressure distribution around a noise barrier, a prototype of an acoustical attachment was produced based on the resulting analytical model calculations and numerical analysis. The principle of the Helmholtz resonator was used to optimize the acoustical impedance on the surface of the upper edge of the noise barrier. Using the model it was possible to find an appropriate acoustical property for the impedance according to the target frequency, the sound incidence angle relative to the barrier and according to the receiver position. In this paper the results from the out-door experiment are shown and discussed.