The assessment of the sound reflection of noise barriers is based on different methods like EN 1793-1 by measuring the reverberation time of the diffuse sound field of the room as well as a method for measuring the impulse response by cross correlation according to CEN/TS 1793-5 (Adrienne method) using a non-diffuse sound field near (25 cm) the barrier. These two methods provide different results. The key question, already discussed for several years, is how the sound reflection of noise barriers appears at the acoustical far field which is interesting for consideration of immission points. For this in the course of the research project REFLEX a certain measurement method was developed, which makes sound reflection measurements under certain conditions in the acoustical far field (until 25 m) possible. The research project REFLEX was carried out by the Austrian Institute of Technology (AIT) and the company TAS by order of infrastructural operators (ASFINAG and OBB), federal ministries (BMVIT and BMFLUW) as well as 5 federal states and 8 different manufacturers of noise barriers. The measurement setup and the measurement procedure will be explained. Measurement results on different noise barriers will be represented and compared with common methods (reverberation room, Adrienne).
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