[en] The knowledge of acoustic properties of urban surface (absorption, reflection and diffusion coefficients) is very important in the framework of the noise mapping in urban areas. Indeed, most of noise prediction tools require the use of such coefficients in the boundary equations of the sound propagation models. An indirect method combining experimental data and numerical simulations is then proposed in order to obtain the absorption and scattering coefficients of an urban street. An empirical relationship is first established, linking the scattering variation to an absorption variation. This relation transforms a problem with two variables (absorption and scattering) into a single variable problem (absorption) for a reference scattering coefficient. Secondly, the absorption coefficient is adjusted in order that the numerical results match the experimental data in terms of sound pressure level distribution. Lastly, the obtained value of absorption, associated with the empirical relation, allows to test different absorption and diffusion pairs presenting the same sound level distribution against the experimental reverberation times. Following this procedure, a coefficients pair minimising the discrepancies both on the sound level distribution and the reverberation time is obtained. This method is here applied to a Haussmaniann street. Results show that the obtained absorption coefficients are weak whereas the scattering is quite high, which is physically consistent as the façades are composed of weakly absorbent materials (stone and glass) and fitted with a lot of recesses and protuberances creating scattering.
Disciplines :
Architecture
Author, co-author :
Billon, Alexis ; Université de Liège - ULiège > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Electroacoustique, acoustique appliquée et éclairage
Picaut, Judicaël
Language :
French
Title :
Evaluation des caractéristiques acoustiques d’une rue à partir de mesures
Publication date :
September 2010
Journal title :
Acoustique et Techniques
ISSN :
1263-8072
Publisher :
Centre d'Information et de Documentation sur le Bruit (CIDB), Paris, France
Volume :
62
Pages :
33-38
Name of the research project :
OPALHA
Funders :
ADEME - Agence de l'Environnement et de la Maîtrise de l'Energie
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