Experimental verification of the acoustic performance of diffusive roadside noise barriers

The acoustic performance of pairs of diffusive roadside barriers is tested experimentally on a 1:10 scale model, and compared to that of more traditional specularly reflecting barriers. Significant attenuation benefits are detected not only in the shadow zone behind the barriers, but also in the unprotected zone immediately above the barriers, thus proving that diffusive traffic faces of the barriers may effectively help in counteracting multiple reflection effects. In addition, a radiosity-based theoretical model developed for the evaluation of the sound field behind pairs of diffusive noise barriers is described, and its ability to predict the extra SPL attenuation deriving from the replacement of geometrically reflecting barriers with diffusely reflecting barriers is verified.