Experimental study of the noise directivity of a hybrid electric vehicle

The currently increasing use of Electric and Hybrid Electric vehicles (EV and HEV) has incremented the interest of their interior and exterior NHV behaviour, as well as their interaction with the passengers, pedestrians and noise surrounding. As a matter of fact, it is widely known that the very low noise level radiated by a low-speed approaching HEV is a recognised danger for other vehicles, pedestrians and cyclists, even though this absence of sound is welcoming for the environmental regulations. In order to reduce the danger of those vehicles while moving, several manufacturers and research teams are developing and studying new external noise generators for such vehicles, however, a previous noise external characterization of an EV or HEV does not appear to have been deeply studied. This paper describes and implements a methodology to measure the noise directivity of a Hybrid Electric vehicle using a microphone array under pass-by test conditions.