Effect of additional warning sounds on pedestrians’ detection of electric vehicles: An ecological approach

Effect of Environmental Noise, Distance and Warning Sound on Pedestrians’ Auditory Detectability of Electric Vehicles

“…All participants were informed that normal hearing was a requirement for the test. The frequency of the normal hearing test was set between 500 and 4000 Hz as measured using an audiometer [10]. Three participants were excluded owing to hearing problems or because they misunderstood the test instructions.…”

“…In the past, pedestrians could judge whether a vehicle was approaching or still distant based on the noise it produced [2,8]. However, previous studies such as Cocron and Krems [9], Fleury et al [10] and Pardo-Ferreira et al [11] indicated that electric vehicles generate lower noise levels than ICE vehicles at low speeds, making it more difficult for pedestrians to detect their approach and thereby negatively affecting pedestrian safety [12,13]. Robart and Rosenblum [14] asked participants to estimate the direction of electric vehicles and ICE vehicles moving at 8 km/h through headphones.…”

“…To increase pedestrian safety, the Acoustic Vehicle Alerting System (AVAS) has been used to increase the audibility of electric vehicles and decrease the incidence of traffic accidents involving pedestrians and electric vehicles. Fleury et al [10] tested an electric vehicle with four sound modes-no sound, small pitch shift, large pitch shift, and small pitch shift with modulated sine waves-to analyze the effect of adding external sounds on the detection distance. They found that the addition of external sounds resulted in a larger detection distance (i.e., earlier detection), and that modulating the frequency of these sounds resulted in more efficient detection.…”

“…Therefore, their results might overestimate or underestimate the audibility and detectability of electric vehicles. In addition, some previous studies conducted experiments with real vehicles in outdoor environments [10,13] or recorded vehicle sounds and played them in the laboratory through headphones or speakers [2,8] to evaluate the audibility and detectability of electric vehicle warning sounds. In these studies, participants heard not only warning sounds but also the noise from tires and pavements.…”

“…In these studies, participants heard not only warning sounds but also the noise from tires and pavements. However, different types of tires and pavements will produce different noises, thereby influencing the audibility and detectability of electric vehicles [8,10]. Further, most previous studies recorded the detection distance between the electric vehicle and the participant to evaluate the audibility and detectability of the warning sound of the vehicle.…”