"Research is proving the effectiveness of trees and shrubs as noise abaters—research prompted by the growing awareness that excessive noise is a form of environmental pollution. The average community noise level has risen fourfold in the past 20 years with jet aircraft, the heavy vehicular traffic, and domestic power equipment contributing to the problem. It is likely to go higher if it is not checked." But how many trees does one need? It turns out the that number and types of trees and shrubs is important in creating an effective noise filter. "In some situations trees will reduce noise levels up to 50% but to be effective you need a tree barrier that is at least 50 feet deep. It also needs to be longer than you might expect, and it needs to consist of both trees and shrubs that start at ground level." And, "evergreens are favored for year-round noise screening. " For additional reading on the subject: Trees And Shrubs Can Curb Noise:
