An approach for indoor prediction of the pass-by noise of a vehicle based on the time-domain equivalent source method

Abstract

An approach based on the time-domain equivalent source method (TESM) is developed for the indoor prediction of the pass-by noise of a vehicle in a small-scale semi-anechoic chamber. In the approach, a vehicle drives on a chassis dynamometer, and a number of microphones are distributed around the vehicle to measure the pressure radiated by the vehicle in the near field. Based on the idea of TESM, the sound sources generated by the vehicle are modeled by a series of time-domain equivalent sources, and the sound radiated from these sources to the microphones is depicted by the half-space Green’s function that takes the reflections from the rigid ground into account. To evaluate the pass-by noise, the strengths of equivalent sources are first solved by using the measured pressures as the input of TESM, and then the pressures on the target points specified by the ISO 362-3 Standard are reconstructed by the superposition of sound fields generated by the equivalent sources. Finally, the sound pressure level (SPL) of the pass-by noise can be calculated from the reconstructed pressures. In particular, the proper arrangement scheme for the equivalent sources is investigated in numerical simulations to ensure the prediction accuracy. Numerical and experimental results demonstrate that the proposed approach can effectively predict the SPL of the pass-by noise of a vehicle for both constant-speed and accelerated test conditions in a small-scale semi-anechoic chamber.