The Long-Term Monitoring Site (LTMS) is a continuous monitoring site located in western France. It has been set up by IFSTTAR (ex-LCPC) for a long observation period (10 years) in the aim to better understand the physical phenomena inherent in the field of environmental acoustics. This research topic still encounters some major scientific obstacles despite the interest shown by the international scientific community and despite the resources allocated in this research domain over the past several decades. The double objective of this huge LTMS experimental database is to validate the numerical models (both acoustical and micrometeorological models) and to allow statistical analysis. Statistical studies leads to space representativeness exploration (site effects) by quantifying the influence of micrometeorological conditions on acoustic field variability at the local scale (i.e. site scale), in contrast with the regional scale (i.e. Météo-France weather stations). The statistical data exploration also focuses on temporal aspects (short vs. long term). This paper focus on some examples of such statistical data exploration, in the aim of deriving an estimation of space and time variability of critical sound pressure levels (SPL) on this complex topography site (valley and viaduct) over the short-, medium- and long-term periods. Thus in this paper the studied data are issued from a permanent acquisition (monitoring) over the 2002-2007 period (sampling interval: 10 sec) of sound pressure levels and micrometeorological characteristics at several points and heights on the site. This paper also introduces the LTMS database as a free access tool for all the scientific community.
