绿化带对不同频率城市交通噪声的衰减作用

植物绿化对交通噪声具有一定的阻挡与衰减作用,其衰减效果取决于绿化带的构成、纵深等。研究选取杭州西湖风景区5个绿化带和1个空地区,测量1/3倍频程下交通噪声的衰减情况。结果表明：10 m左右纵深的绿化带可使交通噪声降低3-5 dB;绿化带的降噪效果在中低频要好于高频,最高在315-400 Hz之间;绿化带辅助地形的下降可有效提高降噪效果;绿化带中乔木选用阔叶类植物的降噪量高于针叶类植物3 dB左右,在低频段降噪量的提升要高于中高频段。

Frequency Characteristics of Traffic Noise Attenuated by Green Belts

The plant is a barrier to attenuate traffic noise, and the effect of noise reduction depends on the construction and depth of green belts. Traffic noise attenuation at different 1/3-octave frequencies was measured at five vegetation sites and a control site in Hangzhou Westlake parkland. Traffic noise could be reduced by 3 ~ 5 dB by 10-meter depth green belts. The reduction effect for the middle and low noise frequencies was better than for high frequencies. The maximum noise reduction occurred on the frequencies from 315 to 400 Hz. The effect of noise reduction might be enhanced by the reduction of land elevation. Noise attenuation by hardwoods was 3dB higher than conifers. The reduction was more effective on low noise frequencies than on middle and high frequencies.