Application of the Transmission Line Matrix method for outdoor sound propagation modelling – Part 2: Experimental validation using meteorological data derived from the meso-scale model Meso-NH

Outdoor sound prediction is both a societal concern and a scientific issue. This paper deals with numerical simulations of micrometeorological (temperature and wind) fields for environmental acoustics. These simulations are carried out using the reference meso-scale meteorological model at the Meteo-France weather agency (Meso-NH). Meso-NH predictions at very fine scales (up to 3 m), including new developments (drag force approach), are validated both numerically and experimentally under stable, unstable and neutral conditions. Then, this information can be used as input data for the acoustic propagation model. The time-domain acoustic model is based on the Transmission Line Matrix method. Its development has also been promoted for application to outdoor sound propagation, i.e. to take into account topography, ground impedance, meteorological conditions, etc. In part 1, the presentation and evaluation of the Transmission Line Matrix method showed the relevance of this method's use in the context of environmental acoustics. Finally, simulated noise levels under different propagation conditions were compared to in situ measurements. Satisfactory results were obtained regarding the variability of the observed phenomena. Regarding environmental acoustics, outdoor sound prediction is both a societal concern and a scientific issue. It is now considered that as of 50 m from the sound source, the meteorological effects on sound propagation must be taken into account [1]. In order to qualify and quantify this influence, many acoustical propagation models have been developed. The meteorological information is introduced through an atmospheric model of differing complexity (from the simple linear vertical profile of wind and temperature to a complex representation of the atmospheric boundary layer). In order to obtain such a complex representation of the boundary layer, the purpose of this paper is to use simulation results of the meso-scale meteorological model Meso-NH in Large-Eddy Simulation (LES) configurations. Then, this information can be used as input data for the time-domain sound propagation model: The Transmission Line Matrix (TLM) method. The associated paper (part 1) deals with the presentation and evaluation of the Transmission Line Matrix method in the context of environmental acoustics. In this paper (part 2), the two different models (acousti-cal and meteorological) are compared with experimental data derived from the Lannemezan-2005 campaign. In Section 2, the experimental campaign of Lannemezan-2005 is first presented. An overview of the meso-scale meteorological model Meso-NH and its configuration is given in Section 3. The results obtained by this model over the Lannemezan site are next compared with the meteorological …