The reduction of sound by vegetation is commonly attributed to the processes of reflection, deflection and absorption.Foliage appears to be the most efficient part of a tree for scattering sound and it seems that large leaves are more effective than small leaves. Low shrubs and/or hedges along the edge of a group of trees can improve sound reduction, particularly those on the side nearest the sound source.Noise reduction tends to increase with tree height up to 10-12m after which it tends to decrease. This is probably a result of lower branches dying and allowing sound to travel more easily.

Noise reduction is correlated with the width of a belt of trees, i.e. the wider it is, the greater the noise reduction.The length a tree and shrub belt extends will influence its effectiveness in noise reduction. Actual prescriptions are difficult however, as they will depend on the dimensions of the noise source.A screen placed relatively close to a noise source is more effective than one placed close to the area to be protected. However, at midway between the source and receiver, noise reduction is least.Large-leaved deciduous species may be more effective at reducing noise during spring and summer but evergreens will provide better year-round attenuation.