Electric vehicles are mostly silent, so they emit a special sound when driving at low speeds to alert pedestrians. That sound could theoretically be anything, but the United States has decided against allowing drivers to change it.
Electric vehicles in the United States (and most other countries) are required to play outward-facing sounds when the car is moving at low speeds, much like the beeps from many cars and trucks while in reverse. The sound is an important indicator for anyone walking near an EV, since the cars are otherwise completely silent — excluding the sound of tires rolling on the ground or pavement.
The low-motion sound is usually not configurable, but the United States National Highway Traffic Safety Administration introduced a proposal in 2019 that would have allowed car manufacturers to offer multiple options for the sound. However, according to Reuters, the NHTSA has now dropped the proposal. The agency said, “removing this restriction would allow manufacturers to make more obscure sounds that only appeal to a small minority of (hybrid electric) owners.”
It’s a shame that future EVs (or at least, ones sold in the US) won’t have the option of playing the Star Trek theme or air horns to alert nearby people, but it’s probably for the best. More jarring sounds might startle people, and more subtle sounds could lead fewer people noticing — leading to more injuries. The NHTSA projected that the existing low-level noises prevented 2,400 injuries in 2020.