Including diffuse reflections and obstructions in sound ray calculation codes through a posteriori corrections: case study of a street canyon
CAN ; PICAUT ; FORTIN
Type de document
COMMUNICATION AVEC ACTES INTERNATIONAL (ACTI)
Langue
anglais
Auteur
CAN ; PICAUT ; FORTIN
Résumé / Abstract
Sound ray codes are implemented in most of the market sound propagation models, because of their short computation times and their rather good accuracy. They suffer however two limitations for urban sound propagation calculations: (i) they only consider specular reflections and thus neglect noise scattering on the facades, (ii) they do not account for the obstructions of vehicles or urban furniture on the ray paths. These two phenomena, which play important role in sound propagation within street canyons, are reproduced by the sound particle tracing code SPPS, implemented in the Software I-Simpa, developed at Ifsttar.
In this paper, we rely on I-Simpa to determine the corrections to apply, to include a posteriori noise scattering and obstructions on the ray paths, when calculating sound propagation within street canyons with a model based on ray codes. About thirty thousand simulations are run, covering exhaustively the combinations of typical values taken by the seven following parameters: street width and height, absorption coefficient of the ground and facades, diffusion coefficient of facades, mean free path and absorption coefficient of the obstructions. By subtracting the attenuations calculated to the attenuations obtained under standard conditions (specular reflection and no obstruction), the corrections are calculated as a function of the seven listed parameters. These corrections can help making models based on ray codes more accurate for calculations within street canyons, without increasing computation times.
