Traffic noise and perceived soundscapes: a case study

The present study will deal with a practical problem of noise mapping: the acoustical classification of roads in the medium size municipality of San Giuliano Terme, in Tuscany (I). At first, using a common approach in literature, the main road infrastructures have been classified in three clusters, applying threshold methods to traffic flow measurements. The time history of LAeq was then acquired in selected sites over a continuous period of 24 hours and the power spectrum G(f) was then calculated from dB values of LAeq over 15 minute intervals. A power law was fitted to G(f) in the range [0.02, 0.2] Hz, obtaining two parameters- B(t) and A(t)- over a complete day. Hierarchical clustering was finally performed and the clusters obtained resembled the ones based on traffic flow. The values of B(t) and A(t) have been compared with other indicators: comparison with Number of Noise Event (NNE) and L10-L90 has been reported here. New fitting possibilities for G(f) has also been explored and discussed in this work. Finally, statistical analysis has been used to get further information on the meaning of B.