This work is part of as tudy dealing with city-dwellers' quality of life. Noise is known to be an important factor influencing the quality of life. In order to diagnose it properly,w ep ropose an oise monitoring system of urban areas. It is based on the use of large microphone arrays in order to extract the radiated sound field from each passing-by vehicle in typical urban scenes. Amachine learning algorithm is trained so as to classify these extracted signals in clusters combining both the vehicle type and the driving conditions. This system makes it possible to monitor the evolution of the noise levels for each cluster.T he proposed system wasfi rst tested on passing-by isolated vehicles measurements and then implemented in areal street in Paris (France).