Noise reduction by greening

Attenborough, Keith and Taherzadeh, Shahram (2023). Noise reduction by greening. Academia Engineering, 1(1)

DOI: https://doi.org/10.20935/acadeng6114

Abstract

Greening the environment can improve soundscapes by reducing unwanted sounds and introducing sounds that are generally considered more desirable. This review concentrates on the physics by which increasing the area of natural ground cover and vegetation can reduce sound levels. Most naturally occurring ground surfaces are porous. If a source of sound and a listener are close to a porous ground surface, the sound reflected from the surface combines with sound traveling directly to the listener such that the phase difference due to the path length difference adds to the phase change during reflection at the surface. At the listener, the two components will partly cancel each other; in other words, the direct and reflected waves interfere destructively, and there is a reduction in the total sound level over a range of frequencies. Also, viscous drag and heat exchange at leaf surfaces adds to sound attenuation. Measurements and predictions show that the viscous and thermal processes and ‘soft’ ground effect are the most important contributors to sound attenuation through crops and densely planted trees and contribute to the acoustical influences of roof top gardens and vegetated façades. Although widely used schemes for predicting outdoor noise allow for a porous ground effect and for attenuation through foliage, they are not sufficiently accurate either to explore the potential of ‘greening’ for noise reduction or to be useful in devising plans to exploit it. Improved prediction schemes are key to realizing the potential of greening for noise reduction.

Viewing alternatives

Metrics

Item Actions

Export

You can export this page using these formats Digital Object Identifier - DOI