Measurement of the contribution of each individual vehicle to the road traffic noise

Road traffic is the main noise source in urban environments. While it is feasible to measure the noise emitted by road vehicles in standard conditions [ISO 11819‐1;2, ISO 362], nowadays it is not possible to detect the contribution of each vehicle to the overall road traffic noise in real driving conditions. However, some authors have demonstrated previously that there is a high correlation between maximum noise levels and mean annoyance. Therefore, an efficient control procedure to reduce road traffic noise annoyance should be to identify those vehicles contributing with the maximum noise levels. The main goal of this paper is to describe a boarded acoustic system to measure the contribution of each vehicle to the overall road traffic noise. The system consists of two microphones, one close to the tire furthest from the exhaust duct, and the other close to the engine air intake. The signals picked up by these microphones are processed to calculate the evolution of the Leq,1s and the levels histogram along the driving path. The tests carried out in an urban circuit in Madrid (Spain), with two cars (gasoline and diesel) and five drivers, demonstrate that it is possible to detect those especially noisy vehicles.