Prediction of vehicle pass-by noise

Environmental noise exposure represents a burden to people and can result in cardiovascular disease, sleep disturbance or annoyance. Road traffic noise is a main contributor to environmental noise, thus, it is intended to be reduced and limited by legislation in order to increase health and life quality. Vehicle pass-by noise tests are conducted according to the international standard ISO 362, which is suppose to reflect the noise emission of a vehicle in an urban traffic environment. It is discussed that nowadays urban traffic situation requires a change of the test procedure with accompanying reductions in pass-by noise limits. To achieve compliance with the pass-by noise test it is important that vehicle engineers have access to predictive tools at the design stage. In this paper the initial development of a pass-by noise predictive tool is reported. To begin with, the vehicle pass-by noise test according to standard ISO 362 is summarized. Existing public domain literature is reviewed and an analysis of the characteristics of the four major noise sources (engine, intake and exhaust system, tyre/road system) contributing to pass-by noise is presented. An experimental set-up involving a point source loudspeaker on a moving trolley is described. Experimental measurements made within an anechoic chamber are used as validation data for the predicted pass-by noise.