Sound field of subway platforms with complex forms

Abstract

While the sound field characteristics of idealised long enclosures have been demonstrated, this study aimed to reveal the sound field of subway platforms with complex forms. The sound fields of ten actual subway platforms with complex forms were simulated, and the sound pressure level (SPL) attenuation and reverberation time (RT 30) were analysed. The results indicated that the average SPL attenuations of actual platforms with complex forms were 3.0 ∼ 7.7 dB greater than that with a corresponding idealised long enclosure, and the average RT 30 was 0.1 ∼ 0.5 s shorter. Regarding the receivers along the length, with the source-receiver distance increasing, the SPL attenuation showed an approximately logarithmic curve, and RT 30 presented a slightly increasing trend. The distance from the centre of each protruding space to the source was linearly correlated to both the average SPL attenuation and average RT 30 in each space. The geometrical parameters of ground perimeter, ground area, and average width were negatively correlated with the average SPL attenuation, and they were not significantly correlated with the average RT 30 for the actual subway platforms with complex forms. These results are expected to provide a reference for the design of underground subway platforms, acoustic environment controls, and soundscapes.