Sound source contributions for the prediction of vehicle pass-by noise

Current European legislation aims to limit vehicle noise emissions since many people are exposed to road traffic noise in urban areas. Vehicle pass-by noise is measured according to the international standard ISO 362 in Europe. More recent investigations of urban traffic have led to the proposal of a revised ISO 362 which includes a constant-speed test in addition to the traditional accelerated test in order to determine the pass-by noise value. In order to meet the legal pass-by noise requirements, vehicle manufacturers and suppliers must analyse and quantify vehicle noise source characteristics during the development phase of the vehicle. In addition, predictive tools need to be available for the estimation of the final pass-by noise value. This thesis aims to contribute to the understanding of vehicle pass-by noise and of the characteristics of the vehicle noise sources contributing to pass-by noise. This is supported through an extensive literature review in which current pass-by noise prediction methods are reviewed as well. Furthermore, three vehicle noise sources are replicated experimentally under laboratory conditions. This involves an orifice noise source, represented by a specially designed loudspeaker on a moving trolley, shell noise, represented by a metal cylinder structure, and tyre cavity and sidewall noise, represented by an annular membrane mounted on a tyre-like structure. The experimentally determined directivity characteristics of the acoustically excited noise sources are utilised in the pass-by noise prediction method. The predictive results are validated against experimental measurements of the three vehicle-like noise sources made within an anechoic chamber

Sound source contributions for the prediction of vehicle pass-by noise

Road traffic noise contributes to environmental noise, which can result in cardiovascular disease, sleep disturbance or annoyance for the exposed population1. The reduction of road traffic noise aims to increase health and life quality. Therefore, the vehicle pass-by noise emission, which is determined in a standardised test situation, was limited by legislation. First introduced in the 1970s, vehicle pass-by noise limits have been gradually reduced for all vehicle classes. However, road traffic noise was not as significantly reduced as the pass-by noise limits

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

Noise source characteristics in the ISO 362 vehicle pass-by noise test: literature review

Since many people are exposed to road traffic noise in urban areas, current legislation aims to limit vehicle noise emissions. In Europe, the vehicle pass-by noise test is implemented according to the international standard ISO 362. As a result of more recent investigations of urban traffic, a revision to the ISO 362 standard has been proposed that includes a constantspeed test in addition to the traditional accelerated test in order to determine the pass-by noise value. To ensure compliance with the pass-by noise test vehicle manufacturers and suppliers must quantify vehicle noise source characteristics during the design stage of the vehicle. In addition, predictive tools need to be available during the product development phase in order to estimate the final pass-by noise level. In this paper an extensive literature survey is presented of noise source characteristics in the ISO 362 vehicle pass-by noise test. Vehicle pass-by noise is analysed in the time and frequency domains and a ranking of the noise source contributions is established. The characteristics of the four major noise sources (engine, intake system, exhaust system, tyre/road system) contributing to pass-by noise as well as current prediction methods are reviewed