A European Life project, Dynamap, has been devoted to provide a real image of the noise generated by vehicular traffic in urban and suburban areas developing a dynamic acoustic map based on a limited number of low-cost permanent noise monitoring stations. In the urban area of Milan, the system has been implemented over the pilot area named District 9. Traffic noise data, collected by the monitoring stations, each one representative of a number of roads within the zone sharing similar characteristics (e.g. daily traffic flow) and otherwise called ?group?, are used to build-up a ?real time? noise map. An important aspect of this project regards the ?contemporaneity? of noise fluctuations predicted by Dynamap with those effectively measured at an arbitrary location. Integration times heavily affect the result, with correlation coefficients up to 0.8-0.9 for updating times of 1h. As Dynamap has a statistically-based approach, higher correlations are observed when averaging over groups of roads with similar traffic flow characteristics.