Evaluation of Multiple Electric Vehicle Sources and New Concepts Regarding Speed-Dependency

In today's urban environment inhabitants are permanently exposed to elevated noise levels, which are dominated by traffic noise. The process of electrification of vehicles might change the traffic noise in city centers. The aim of this work was to determine the pedestrian reaction, the warning effect and the annoyance of more realistic traffic situations. For this purpose both combustion and electric vehicle noise situations and mixed scenarios of both concepts were generated. The differences in the perceived annoyance and warning effect were investigated with perception studies.

It was found that that it is not possible to predict an overall annoyance of multiple vehicles with the same sound passing by in a short time span from the annoyance rating of the single vehicle with this sound: In some cases the order of the annoyance ratings will change: a single electric vehicle, which was perceived as least annoying, was evaluated as the most annoying noise by the increase to eight vehicles. The background noise also has an impact on the perception of annoyance and the warning effect. Furthermore the sound level of a full speed-scaling of an approaching vehicle starting from 0 km/h at the critical distance is nearly 10 dB below the level at a constant speed of 10 km/h. Therefore some variants of additional sounds were generated, in which the sound level below 5 or 10 km/h is not reduced depending on vehicle speed. The results show that the change of the speed-scaling influences the detection time of an approaching vehicle enormously.