To be effective, an acoustic barrier needs to be placed as close as possible either to the noise source or the receiving position. There should be no gap or joint in the barrier through which noise will leak. The surface density of the barrier must be at least 10 kg/m2. Ideally, the length of the barrier should be at least 5 times its height. Line of sight between the source and the receiver must be cut off completely.

A reduction of noise level of between 5 dB(A) to 10 dB(A) can generally be resulted. Noise reduction will be greater if the barrier is lined with sound absorbing material at the surface of the barrier facing the noise source or is extended as high as possible above the line of sight.

Figure 51: Barriers