Experiments and computations of noise reduction by barriers

Abstract

Experimental and theoretical investigations are presented of the performance of noise barriers in the open air. The experimental work includes full-scale measurements on barriers and scale-model measurements on a barrier in a wind tunnel. The wind tunnel experiments indicate that meteorology has large effects on barrier attenuation. The results of the wind tunnel experiments are compared with results of numerical computations with the parabolic equation method. Good agreement with the experimental data is obtained only if wind speed profiles as measured in the wind tunnel are used in the computations. It is concluded that wind speed gradients induced by the barrier itself reduce the barrier attenuation considerably: reductions as large as 10 dB are found. The use of aerodynamically optimized barriers is proposed in order to minimize this reduction of barrier attenuation.