image: A listening test for an electric vehicle.
Credit: Mei Suzuki
HONOLULU, Dec. 1, 2025 — One of the many benefits of electric vehicles is that they are much quieter than traditional gasoline-powered vehicles. In some cases, though, they are too quiet. Automakers are required to design their vehicles so they emit sounds at low speeds to alert pedestrians to their presence.
However, aside from some basic regulations regarding volume, automakers are free to choose whatever noise they wish their vehicles to emit. This freedom gives researchers a unique opportunity to design custom sounds to maximize their effectiveness.
Graduate student Mei Suzuki will present her team’s efforts to design custom approach sounds for electric vehicles Monday, Dec. 1, at 2:35 p.m. HST as part of the Sixth Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan, running Dec. 1-5 in Honolulu, Hawaii.
“In our research, we aimed to design approach-informing sounds based on onomatopoeia that [are] evoked by the image of a ‘quiet vehicle,’” said Suzuki. “These stimuli included sounds created based on onomatopoeic sounds and pink noise.”
To test their library of created sounds, the team played them to volunteers, both in a studio and in real road conditions. They then asked the volunteers to rate each based on criteria such as “The sound has a sense of urgency” and “The sound is easy to notice.” The noises were then ranked based on this feedback.
They found the best performer was a version of pink noise — a type of noise dominated by lower-frequency notes.
“The reason this sound stimulus was rated highest was its strong low-frequency components and its similarity to automotive running noise,” said Suzuki.
This low-frequency noise distribution was less susceptible to being drowned out by other sources of ambient noise, which meant that approaching vehicles could be heard clearly by the volunteers in all conditions.
The researchers are planning to introduce similar sounds for electric bicycles, e-scooters, and other small lightweight mobility devices.
“Starting this year, we are conducting research on the sound design of approach warning sounds specifically for micromobility devices,” said Suzuki. “Since research on approach warning sounds for micromobility devices is largely unexplored, we believe this could contribute to reducing collisions involving pedestrians and visually impaired individuals.”
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Main Meeting Website: https://acousticalsociety.org/honolulu-2025/
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ABOUT THE ACOUSTICAL SOCIETY OF AMERICA
The Acoustical Society of America is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world’s leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.
ABOUT THE ACOUSTICAL SOCIETY OF JAPAN
ASJ publishes a monthly journal in Japanese, the Journal of the Acoustical Society of Japan, as well as a bimonthly journal in English, Acoustical Science and Technology, which is available online at no cost https://www.jstage.jst.go.jp/browse/ast. These journals include technical papers and review papers. Special issues are occasionally organized and published. The Society also publishes textbooks and reference books to promote acoustics associated with various topics. See https://acoustics.jp/en/.
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