WSU Graduate Researcher Mei Suzuki Engineers New EV Warning Sounds for Safer Streets
- MM24 News Desk
- 4 days ago
- 3 min read
Credit: Mei Suzuki
Graduate student Mei Suzuki from Washington State University has tapped into the power of low-frequency noise, designing custom alert sounds for quiet electric vehicles. Her research team discovered that specific sound profiles, including a modified version of pink noise, are most effective at cutting through urban din to warn pedestrians. The findings, presented at a major acoustics conference, offer a blueprint for making future EVs and e-scooters safer.
For years, we’ve been told that silent electric vehicles pose a danger to pedestrians. In response, regulations now require EVs to emit artificial warning sounds at low speeds. But if we have to add sound, shouldn't we make it the best sound possible? That’s the question driving the work of Mei Suzuki, a graduate researcher at Washington State University. Her team isn’t just adding beeps; they’re using acoustic science to design sounds that genuinely protect people.
Presented at the Sixth Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan in Honolulu, the research sought to craft the optimal auditory cue. “In our research, we aimed to design approach-informing sounds based on onomatopoeia that [are] evoked by the image of a ‘quiet vehicle,’” Suzuki explained. The team created a library of sounds, from synthesized onomatopoeic words to engineered pink noise, which emphasizes lower frequencies.
The testing phase was rigorous. Volunteers listened to these sounds in both controlled studio environments and on actual, noisy streets. They rated each sound on its urgency, noticeability, and overall appropriateness. The clear winner wasn't a futuristic whistle or a synthetic chime.
According to the team’s findings, reported in their conference presentation, the top performer was a version of that pink noise. “The reason this sound stimulus was rated highest was its strong low-frequency components and its similarity to automotive running noise,” said Suzuki.
Why do low frequencies work so well? Imagine the soundscape of a busy city: horns, chatter, wind, and the general high-frequency buzz of activity. A low-frequency rumble cuts through that clutter more effectively, traveling farther and with less distortion.
This makes the approaching vehicle detectable from a safer distance, giving pedestrians—especially those who are visually impaired—critical extra seconds to react. The research essentially proves that the most effective alert sound is one that works with the physics of sound in real-world conditions, not against it.
This work moves beyond simply checking a regulatory box. It’s about functional, intelligent design that places pedestrian safety at the forefront of the electric mobility revolution. The implications are significant for automakers who now have data-driven guidance. Instead of choosing a sound for brand identity alone, they can prioritize acoustic efficacy, potentially saving lives.
The team’s mission is already expanding. “Starting this year, we are conducting research on the sound design of approach warning sounds specifically for micromobility devices,” Suzuki stated. This next phase is crucial, as the silent approach of e-scooters and electric bicycles presents a growing urban hazard. The problem is widespread, but Suzuki noted that research in this area is scarce, making their work a vital step forward.
Ultimately, the goal is a universal language of safety for our streets. As Suzuki’s research demonstrates, the ideal sound is not the loudest or the most jarring, but the one engineered to be heard. In a world filling with quiet electric vehicles, her team’s work ensures those vehicles won’t go unnoticed.
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