American Journal of Environmental Science and Engineering 2019; 3(3): 47-51 http://www.sciencepublishinggroup.com/j/ajese doi: 10.11648/j.ajese.20190303.11 ISSN: 2578-7985 (Print); ISSN: 2578-7993 (Online) A Case Study: The Urban Residents’ Choice for Electric Vehicles Warning Sounds Mia Suhanek * , Ivan Djurek, Antonio Petosic Department of Electroacoustics, Faculty of Electrical Engineering and Computing, University of Zagreb, Zagreb, Croatia Email address: * Corresponding author To cite this article: Mia Suhanek, Ivan Djurek, Antonio Petosic. A Case Study: The Urban Residents’ Choice for Electric Vehicles Warning Sounds. American Journal of Environmental Science and Engineering. Special Issue: Smart Cities – Innovative Approaches. Vol. 3, No. 3, 2019, pp. 47-51. doi: 10.11648/j.ajese.20190303.11 Received: September 18, 2019; Accepted: October 15, 2019; Published: October 23, 2019 Abstract: Nowadays, people are exposed to noise on a daily basis. Therefore, in an overvibrant urban environments electrical vehicles operating at low speed are too quiet to be detected by pedestrians (especially vulnerable group are visually impaired people) and urban residents in general. Thus, electric vehicle warning sounds are sounds created to alert and warn pedestrians to the presence of electrical vehicles (e.g. hybrid electric vehicles, plug-in hybrid electric vehicles and all-electric vehicles) moving at low speeds. The goal of this paper is to determine through a case study what the pedestrians would desire and prefer the electrical vehicle warning audio signals to sound like. The case study involved 201 participants who had the task to fulfil a specially designed questionnaire for this purpose. Regarding the questionnaire, the participants were not prepared in any way for the testing they were just advised to keep in mind that the warning sound they select for the “role” of a pedestrian should not be irritable at the same time for the “role” of a driver. The results obtained from the questionnaire were analyzed and discussed in the paper. When speaking about the concept of smart cities and the legislation around the whole world today this is certainly a hot topic where the opinion of pedestrians and future drivers should not be overlooked. Keywords: Electric Vehicle, Warning Sounds, Audio Signal, Pedestrian Safety, Smart Cities 1. Introduction People are exposed to different sound environments on a daily basis. Noise pollution is often overlooked when compared to other different environmental pollutions (e.g. air pollution, water pollution, soil pollution etc.). Long exposure to noise pollution can be displayed as a bad mood, fatigue, insomnia, headache and loss of concentration, which causes reduced work ability and ultimately permanent hearing impairment [1-3]. Concerning the noise pollution, electrical vehicles represent the future especially when compared to vehicles with internal combustion engine [4] (see Figure 1 [5]). However, at low speeds electrical vehicles produce very little noise, or to say it even harshly, in these urban environments they are practically inaudible. For example, the noise level difference between an electrical vehicle and one with an internal combustion engine (ICE) can be as large as 6 dB(A) at 10 km/h [6]. Unfortunately, much later, when developing higher speeds both types of cars become equally loud mainly due to tires noise. In urban environments, for pedestrians (especially the visually impaired ones) this significantly lower sound level makes it quite difficult to detect electrical vehicles [6]. Since 2009 the Japanese government, the U.S. Congress and the European Commission are studying legislation in order to determine a minimum level of sound for plug-in electric and hybrid electric vehicles when operating in electric mode, so that visually impaired people, other pedestrians and cyclists can hear them coming and detect from which direction they are approaching. Several tests and research have shown that vehicles operating in electric mode can be particularly hard to hear below 32 km/h [7-10].