ČSN EN 16272-6

Noise barriers installed along railways need to provide adequate sound insulation so that sound transmitted directly through the device is not significant compared to the sound diffracted over the top. This European Standard specifies a test method for assessing the airborne sound insulation performance of noise barriers and related devices acting on airborne sound propagation designed for railways in non-reverberant conditions (a measure of intrinsic performance). It can be applied in situ, i.e. where the noise barriers are installed. The method can be applied without damaging the surface. The method can be used to qualify products to be installed along railways as well as to verify the compliance of installed noise barriers to design specifications. Regular application of the method can be used to verify the long term performance of noise barriers. The method requires the averaging of results of measurements taken at different points behind the device under test. The method is able to investigate flat and non-flat products. The measurement results of this method for airborne sound insulation are comparable but not identical with the results of the EN 16272-2 method, mainly because the present method uses a directional sound field, while the EN 16272-2 method assumes a diffuse sound field (where all angles of incidence are equally probable). The test method described in this European Standard should not be used to determine the intrinsic characteristics of airborne sound insulation for noise barriers to be installed in reverberant conditions, e.g. inside tunnels or deep trenches or under covers or very close to the rail track. For the purpose of this European standard reverberant conditions are defined based on the geometric envelope, e, across the rail formed by the barriers, trench sides or buildings (the envelope does not include the railway surface) as shown by the dashed lines in Figure 1. Conditions are defined as being reverberant when the percentage of open space in the envelope is less than or equal to 25 %, i.e.: Reverberant conditions occur when w/e <= 0,25, where e = (w + h1 + h2) This criterion is applied also to the open space between the train body and the barrier surface.