A B S T R A C TSince 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.

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A comparison between transfer path analysis and operational path analysis methods using an electric vehicle is presented in this study. Structure-borne noise paths to the cabin from different engine and suspension points have been considered. To realise these methods, two types of test have been performed; operational tests on a rolling road and hammer tests in static conditions. The main aim of this work is assessing the critical paths which are transmitting the structure-borne vibrations from the electric vehicle's vibration sources to the driver's ear. This assessment includes the analysis of the noise contribution of each path depending on the frequency and vehicle speed range and moreover, the assessment of the path noise impact for harmonic orders which arise due to the physical components of the electric vehicle. Furthermore, the applicability of these methods to electric vehicles is assessed as these techniques have been extensively used for vehicles powered with internal combustion engines

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