Studies On The Noise Reduction And Its Influencing Factors Of Some Landscape Plants In Beijing

A measurement on noise abatement and effect on the different sound spectra of4kinds of landscape plants in Beijing was undertaken by using AWA6288-type Multi-function sound level and TrueRTA audio analysis software, and made every plant’s structure feature quantitative in order to seek the impact factor closely related to noise reduction, establishing the linear model between the amount of noise reduction evaluation and related structural characteristics factor. Test will also take temperature and humidity on acoustic propagation direction into consideration, better to study its effect on sound attenuation by sound through plant. The conclusions are follows:(1)Different growth type plant has different average level A sound noise-reduction capability and noise-reduction rate. Overall, the broad-leaved arbor trees<broad-leaved shrubs<Needle scale leaf species<broad-leaved hedge balls.(2) Different plant in the same growth type also exist significant differences in the noise reduction function. In plant species of being studied, Salix babylonica’s relative A level of noise reduction and noise-reduction rate was relatively minimal among the broad-leaved trees, only0.163dB/m,9%; while Aesculus chinensis’s noise-reduction rate was relatively the strongest, reaching29.97%; Punica granatum had weakest noise-reduction ability among broad-leaved shrubs, while Viburmum sargentii was relatively best; Pinus tabulaeformis’s ability of reducing noise was worst while Sabina chinensis ’kaizuka’ was relatively best in pine needle scale leaves species having studied. The Buxus’s capability of noise-reduction was the strongest, while Barberry ball ranked last in four broad-leaved hedge balls.(3) The top5factors of coniferous species and broad-leaved species impacted on noise reduction capabilities can be summarized as leaf factor. The leaf density on sound propagation direction of crown width than leaf density of first cube of sound first contacted plant had more effect on plant’s noise- reduction ability; the broad-leaved arbor trees and needle scale leaf species’s relative noise-reduction was positively related to the temperature on sound propagation direction, and negatively correlated with humidity.(4)Leaf size (leaf area), tilt state (leaf angle), the leaves density (leaf area index), average crown4factors were the most important factors that influenced noise abatement of broad-leaved shrubs. Leaves dense degree (the leaf density on sound propagation direction, leaf area index), canopy morphology (crown volume, crown)2structural features that affect noise reduction of conifer species most.(5) All plants had unobvious effect on noise reduction at low frequencies, or even negative, but had strong noise-reduction capability in the high frequency, sound absorption mainly rely on high-frequency, most plant’s peak inflection point of noise-reduction appear at250Hz and2kHz respectively in low-middle band and middle-high band.