Urban acoustic imaging : from measurement to the soundscape perception evaluation

Characterising the urban sonic environment is usually done by measuring the energetic indicators such as the average A-weighted level.The European 2002/49/EC directive compels large cities to establish noise maps and pursue action plans aimed at reducing the percentage of citizens exposed to excessive noise levels. In parallel the soundscape concept introduced by Raymond Murray Schafer aims to quantify the urban sonic environment with a global approach taking into account the nature of sources, the context of listening or the habituation. In a complementary approach, our work seeks to quantify the urban soundscape locally using acoustic level maps produced using antennas with a very large number of microphones (up to 256). This method seeks to detect and locate the numerous sources potentially present in the area of interest, but also to assess their instantaneous and averaged acoustic level and spectrum. This paper presents the experimental set-up implementing acoustic arrays based on digital MEMS microphones together with their digital recording system. We present the analysis of a benchmarking campaign led to build a database characterizing various vehicles in different urban-like scenarios. Finally, we investigate new methods so as to combine these objective data and improved annoyance models.