  Electric and hybrid vehicles are growing in popularity. While these vehicles
produce less pollution, they also produce less audible noise, especially at
lower speeds. This makes it harder for pedestrians and cyclists to detect an
approaching vehicle. Thus, an additional system is required to detect electric
and hybrid vehicles and alert pedestrians and cyclists of their whereabouts,
especially while these vehicles are driving at low speeds in cities. This paper
introduces one such method based on high frequency audio emissions that are
present in EVs, which arise, for example, from the process of magnetostriction.
Our method is tested experimentally using 4 different tests vehicles, and a
preliminary EV detection algorithm is also presented.
