Due to increasing traffic and regulations specifying lower noise levels, noise barrier heights are being increased in Austria and other countries. The increasing height disturbs the free sight into the environment. Outward bended noise barriers with high absorptive material can reduce the noise with respect to a straight noise barrier. Calculations based on the boundary element method in two dimensions were made. The results of the calculations are the insertion losses on a grid behind the noise barrier. At the reference position of 25m distance and 2m height (Figure 1), the calculated spectral insertion loss is used as a filter for the measured noise of a motorway or railway line to simulate the noise behind the noise barrier.
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