On Factors of Noise Emitted by a Small Vehicle and Noise Level Simulation of Pass-By Test

To achieve a reduction in the exterior noise of a small vehicle at an early stage of design, we made an attempt to estimate the pass-by noise of the vehicle (ISO R-362 test standards) from measurements of the noise of the engine and exhaust system units. Accordingly, the factors producing exterior vehicle noise, viz., operating condition, noise source and noise propagation were considered, and it was found that the frequency spectrum of the noise source should be taken into account to more precisely estimate noise level and noise spectrum, since the characteristics of noise propagation depend on frequency.