Questionnaire survey on the sound of quiet vehicles

Knowledge of social demands and feasible acoustic properties regarding the acoustic information is strongly required to discuss the measures to take against the potential dangers for pedestrians due to the quietness of hybrid (HV) and electric vehicles (EV). The authors conducted a questionnaire survey on the sound of quiet vehicles in Japan and Germany, and collected 131 total responses. The questionnaire consisted of the questions concerning the sound of quiet vehicles, people's experience that they felt sense of danger due to unawareness of an approaching vehicle, their experiences with encountering a HV/EV, and their attitudes regarding measures being taken to address the problem of quiet vehicles. Situations of encountering danger, as both a driver and a pedestrian, were similar between the survey sites. The results showed that approximately 50% of drivers who drove non-HV/EVs experienced a feeling dangerous due to pedestrians' unawareness of their car, and approximately 60% of pedestrians experienced a feeling dangerous due to their unawareness of a car approaching. Moreover, our results showed that there were a considerable number of pedestrians in their twenties and younger who experienced the dangerous situations due to their use of headphones. These results are discussed in this paper and are compared to previous research and the published guidelines.