A sound library was created and evaluated in both lab and street settings to assess urgency and perceptibility, resulting in a prioritized ranking of sounds.

A team led by a Japanese acoustic researcher tested artificial driving sounds for quiet electric vehicles and found that deeper, low-frequency signals are most effective for warning pedestrians and cyclists.

Researchers plan to extend the approach to smaller vehicles such as e-bikes and e-scooters to further enhance traffic safety and prevent collisions.

Inspired by Japanese onomatopoeia, the team designed sounds that resemble engine noises but remain clearly recognizable, with plans to adapt similar signals for micromobility devices.

The top-performing sounds feature a high proportion of pink noise, since its low-frequency content is less masked by ambient noise and more detectable across conditions.

Laboratory and street tests show that low-frequency sounds are more noticeable and perceived as urgent and acceptable in noisy urban environments, aiding pedestrian safety including for visually impaired individuals.

Volunteer testing in studio and real-road settings ranked sounds by urgency and noticeability, with pink-noise-based designs performing best.

The sound design combines onomatopoeia concepts with pink noise to emphasize low frequencies, producing a resemblance to engine sounds while remaining easily perceptible.

The findings were presented at a joint congress of the Acoustical Society of America and the Acoustical Society of Japan in Honolulu, underscoring both academic and practical urban-safety implications.

Low-frequency, pink-noise–rich sounds improve recognition of approaching EVs and are less easily masked by surroundings.

The top sound includes strong low-frequency components similar to running automotive noise, making it less susceptible to masking and clearer at low speeds.

The work is part of ongoing efforts to refine Acoustic Vehicle Alerting System (AVAS) signals for vehicles under 20 km/h, including regulatory compliance and effectiveness in Germany and beyond.