What Should an Electric Vehicle Sound like?

While some people might think that the near-silent operation of electric vehicles (EVs) is a good thing, there are some drawbacks, certainly as regards the safety of pedestrians or cyclists, who may be caught unawares.

According to a while paper on external sounds for EVs, titled “White Paper on External Sounds for Electric Cars,” released by Danish firms ECTunes and DELTA SenseLab, with contributions by Sonic Minds and iCapture, funded in part by the Danish Sound Technology Network, while the need for sounds is deemed to be important, in the words of Jesper Boie Rasmussen, CEO of ECTunes, “Our challenge is to customize the sound to match the situation without being annoying or creating unnecessary noise.”

According to the report, there should be sounds for (1) starting, (2) forward motion, and (3) reverse motion. Which pretty much accounts for everything except for idling.

The researchers recommend that the starting sound last no more than two seconds.

The forward motion sound should be a “non-melodious engine-like sound.” So as the EV accelerates, there would be the sound of what a car powered by an internal combustion engine would sound like, including a change in character tone when the vehicle’s speed changes. This noise would be generated until the car reaches 25 km/hr (15.5 mph), at which point there is sufficient wind and tire noise to alert pedestrians and cyclists.

The reverse motion would be “an additional sound on top of the driving sound—similar to a regular combustion engine car.”

They’ve determined that loud speakers on the corners of the EV would be optimal, but that the noises could be produced by just two. The loudspeakers would need to be handling sound frequencies between 200 and 2,000 Hz and sound levels up to 70 dB(A) at two meters

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