Modeling the impact of traffic noise: analysis of lightning geometry and its contribution to direct, specular and diffuse path propagation.

The evaluation of urban noise is an important tool in noise control. From existing sources of noise, vehicular traffic is considered the main cause of discomfort in the population. The intensity of the noise that reaches the receiver depends on the level of sound power emitted by the source and the attenuation that occurred in the propagation medium. The analysis of the dispersion of rays in different urban geometries allows the evaluation of parameters that influence the trajectory of noise. The objective of this study is to analyze the contribution of the energy fraction of each path in different urban settings in the global noise, to contribute to the analysis and adoption of mitigating measures. For this, the mathematical model of prediction of noise levels was adopted, which calculates the direct and specular (source-image method) and diffuse (radiosity method) paths. The study was applied in two sectors of the city of Maringá, Brazil. In total, 73200 paths were evaluated in 14640 readings of source positions in 54 measured points. The results showed the part of contribution that each path represents in the acoustic field, and the sound decay caused by obstacles, urban geometry, distance and material properties.