Field Test and Analysis of Noise Reduction Performance of High-Speed Railway Semi-Closed Sound Barriers

Semi-closed sound barriers are increasingly used in high-speed railway engineering, however, research on its noise reduction effect in operation is extremely limited. Based on the Shanghai to Kunming passenger line, noise measurement points were respectively arranged on the inner and outer surface of the semi-closed sound barrier, and the opened and closed sides, at different distances. Noise signals during high-speed train passing-by were monitored. Acoustic characteristics in terms of sound pressure level spectrum, sound field distribution, attenuation law, sound insulation and insertion loss were discussed. Results indicate that the reverberation effect caused by multiple reflections increases the noise on the inner surface of the semi-closed sound barrier; at a distance of 7.5 m from the track centerline, the sound pressure level of the higher measuring point is larger than that of the lower measuring point, and the directivity of the noise distribution is not evident for other measuring points at different heights. The sound insulation of the semi-closed sound barrier increases with the increase in frequency and reaches a peak of 26 dB at 1000 Hz; the insertion loss at a distance of 7.5 m and 25 m from the track centerline is 16.5 dB(A) and 15.5 dB(A), respectively.