Noise Indicators to Diagnose Urban Sound Environments at Multiple Spatial Scales

摘要

The diagnosis of urban sound environments requires noise indicators able to capture its main physical characteristics. However, the more information furnished by indicators, the longer the measurements should be and the lesser immediate their understanding is. In this paper, a three-step methodology is proposed to diagnose urban sound environments at the neighborhood level, with an increasing level of detail that offers some flexibility to the decision maker when investigating the sound quality of a neighborhood. The first step consists in calculating three sound structure indicators, namely the L-50,L-A, sigma(Leq,A), and SGC([50Hz-10kHz]), which allow a continuous spatial categorization of the neighborhood. The second step rests on the calculation of sound events indicators, namely the L-1,L-A, MILA50+10 and MILLF50+15, which are sensitive to the physical dimensions of noise emergences (threshold values, suddenness, occurrences). The third step entails a map of the emergences, which precisely describes the number and the duration of the emergences at a given location. The procedure is validated over three measurement campaigns achieved in January, April and June, when geo-referenced noise measurements were collected over 18 1h-soundwalk periods in Toulouse (France). A clustering analysis is achieved in order to select the subsets of indicators used for describing sound environments. Although these indicators might differ in theory according to the location, the clustering analysis leads to the same indicators as a previous study achieved on another site, suggesting their possible generalization for further studies. Moreover, the stability in the indicators values between the three different campaigns validates their calculation from short time samples. Finally, the procedure enables describing in detail the time fluctuations of sound environments at both the daily and seasonal scales. These temporal variations can be explained by the land use of the site.