How effective are noise walls and noise berms?
Generally, the effectiveness of a noise berm or noise wall depends on the distance between the listener and the noise source, the distance between the listener and the noise berm/wall, the height of the noise berm/wall above the line-of-sight between the listener and the noise source, and the frequency of breaks in the wall/berm. In general, noise berms are more effective than noise walls due to the bulk of the noise berm. Typically, noise reductions are greatest nearest the noise berm/wall. For a residence located near a 20-foot wall, a reduction of about 10 decibels would be typical. The amount of noise reduction decreases, as the listener moves farther away from the wall, and a reduction in noise would be barely perceptible at distances greater than 500 feet.
