Experts are looking for a new sound to avoid accidents with electric vehicles

Specifically, graduate student Mei Suzuki presents her team’s efforts to design custom approach sounds for electric vehicles at the Sixth Joint Meeting of the Acoustical Society of America and the Acoustical Society of Japan, taking place December 1-5 in Honolulu, United States.

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It should be noted that one of the many advantages of electric vehicles is that they are much quieter than traditional gasoline vehicles. However, in some cases, they are too quiet. Car manufacturers are required to design their vehicles to emit sounds at low speeds to alert pedestrians to their presence. However, aside from some basic loudness regulations, automakers are free to choose the noise they want their vehicles to emit. This freedom gives researchers a unique opportunity to design custom sounds and maximize their effectiveness.

This new research tried to design sounds that guided the approach, based on onomatopoeias, evoked by the image of a ‘silent vehicle. These stimuli included sounds created from onomatopoeic sounds and pink noise. To test their library of created sounds, the team played them to volunteers, both in a studio and under real road conditions. They were then asked to rate each one based on criteria such as ‘The sound conveys urgency’ and ‘The sound is easy to perceive’. The noises were classified based on this feedback.

They discovered that the best-performing sound was a version of pink noise, a type of noise dominated by lower-frequency notes. “The reason this sound stimulus received the highest rating was because of its strong low-frequency components and its similarity to the operating noise of a car,” the researchers comment.

This low-frequency noise distribution was less susceptible to being drowned out by other sources of ambient noise, meaning volunteers could clearly hear approaching vehicles in all conditions.

The researchers now plan to introduce similar sounds for electric bicycles, electric scooters, and other small, lightweight mobility devices. Since research on approach warning sounds for micromobility devices is largely unexplored, they believe this could help reduce collisions with pedestrians and the visually impaired.