This communication deals with road traffic noise characterization, and more precisely with the influence of atmospheric conditions and ground irregularities on noise levels, using statistical analysis of experimental data completed with numerical predictions. In this paper, we are presenting two ways to obtain some useful information on temporal fluctuations of sound levels, using both experimental and/or theoretical models. The first way is based on an experimental monitoring site: some acoustic, meteorological and traffic sensors located on the LCPC experimental site (St-Berthevin, France) provide daily data of sound levels variations over time and space. Thus these experimental data focus on spatial aspects (site effects) as well as temporal aspects (short vs. long term), in the aim of deriving an estimation of space-time variability of critical sound pressure levels (SPL) on any site over short-, medium- and long-term periods. The second way is a theoretical method which is based on the coupling of a micrometeorological model with an acoustical model for long range sound propagation: a series of standard local climatic data, provided either by local meteorological offices or by the long-term monitoring experimental site, is used to simulate hourly profiles of vertical gradients of sound celerity over a very long period and the corresponding hourly sound levels. Classical statistical analysis of the time series of sound levels provide some very useful information on the sound levels estimations over a very long period: long term value, dispersion, seasonal fluctuations, etc. (Author/publisher)
Samenvatting