Design of approach informing sound for quiet vehicles that indicates a car traveling

摘要

Quiet vehicles, such as hybrid and electric vehicles, emit less noise than vehicles having an internal-combustion engine, particularly at low speeds. To prevent accidents resulting from this quietness, acoustic vehicle alerting system has been designed to create approach informing sounds. However, a questionnaire survey that we conducted previously revealed that the recognition rate of the approach informing sound was not high (about 40%). To improve the recognition of the approach informing sound, we designed approach informing sounds using onomatopoeic sounds and evaluated them using an evaluation grid method for carlike sounds. We first obtained onomatopoeic sounds that reflected pedestrians' images of approach informing sounds for quiet vehicles. The obtained onomatopoeic sounds frequently included the vowel "u," the consonants "p" and "b," and long tones. According to acoustic characteristics of the obtained onomatopoeic sounds (such as the fundamental frequency and roughness), we created four sound stimuli as samples of approach informing sound. We conducted an experiment using these sound stimuli and an evaluation grid method to examine the factors that affect the perception of car-like sounds as approach informing sounds. We found that sounds that replicated road noise tended to be evaluated highly as indicative of a car traveling on a road and they are thus suitable for approach informing sounds.