In this paper, the noise shielding efficiency of barriers with an acoustic device mounted on their top edge for reducing sound diffraction is described. The authors have already found that the intrinsic efficiency of the device, which is related to the noise-reducing mechanisms, is a function of the angles of the source and receiver but independent of their radii. In the present paper, a novel procedure based on the previous finding is applied to determine the acoustical efficiencies of practical edge-modifying products in the near field, and the results are utilized in calculations to predict sound diffraction behind the edge-modified barriers in the far field. It is proved that the novel method provides an accurate prediction.
IntroductionIn the ASJ RTN-Model 2003 to predict road traffic noise, a precise computing method of sound propagation is additionally prepared for the situation with complicated boundary condition, and some kinds of spectral model of running vehicle noise are proposed for predictive conditions. In recent Japan, constructions of drainage pavement are being carried out very frequently and widely by the expectation for their noise reduction effect. Therefore, a new prediction method takes account on the condition of drainage pavement. For such a purpose, noise reduction effects on the drainage pavement have been considered, and their simple approximate expressions for numerical calculations could have been obtained. We introduce the circumstances of these considerations and their results as a part of the work establishing the ASJ Mode series.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.