Acoustic evaluation of canopy crowns on noise protection walls
In order to obtain a noise assessment of road structures, models for sound emission and sound propagation must be as accurate as possible. Analytical descriptions of noise barriers with tops – crowns – are unknown in the existing national regulations. On behalf of the Federal Highway Research Institute (BASt), the Gesellschaft für Akustikforschung Dresden mbH determined the acoustic effectiveness of a canopy crown installed on the existing noise protection walls of a viaduct. With the metrological proof on a real traffic noise source, predictions of the relevant immission sound pressure level should be possible by using canopy crowns. Within the scope of the investigation, measures were developed which allow a noise assessment of canopy crowns. However, an acoustic effectiveness of the investigated noise protection wall tops beyond the mere increase of the diffraction edge could not be proven.