noise reduction (by trees)
Foliage, especially large leaves, reflect and scatter the higher frequencies of sound while the ground, and to a lesser extent bark, absorbs lower frequencies. The vegetation is relatively effective if close to the source of the noise (rather than close to the area to be protected) and the effect increases up to height 10–12m.
This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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