The federal government is requiring automakers to include artificial motor sounds in electric and hybrid cars when traveling at low speeds to alert pedestrians, but it wants to give vehicle owners the ability to choose which sounds they use.

In a notice of proposed rule-making, the US National Highway Traffic Safety Administration says drivers should be able to “select the sound they prefer from the set of sounds installed in the vehicle.” But NHTSA is also seeking feedback about whether it should limit the number of fake sounds that manufacturers should be allowed to install.

The proposed rule-making would be an amendment to rules that were finalized in February 2018 requiring EVs and hybrid vehicles to emit sounds at low speeds to prevent injuring pedestrians, especially people who are blind or visually impaired. NHTSA recently extended the deadline to 2020 for full compliance, while vehicles sold in the European Union have until 2021.

Electric cars are quieter than their internal combustion engine-having counterparts

Electric cars are quieter than their internal combustion engine-having counterparts. The only noises EVs usually generate is caused by wind resistance or tire noises, and that is only at moderate to higher speeds.

“The National Highway Traffic Safety Administration is requesting public comment on amending the new Quiet Vehicle safety standard FMVSS No. 141, Minimum Sound Requirements for Hybrid and Electric Vehicles, to allow multiple driver-selectable sounds so long as they meet the existing performance requirements,” an agency spokesperson said in a statement. “NHTSA is considering whether to allow hybrid and electric vehicles to be equipped with a suite of pedestrian alert sounds from which a driver may select a preference.”

The new rule requires all newly manufactured electric vehicles that weigh 10,000 pounds or fewer to make an audible noise when traveling forward or in reverse at speeds of 19 mph or less. NHTSA says the sound alert is not required at higher speeds because other factors, such as tire and wind noise, “provide adequate audible warning to pedestrians.” Initially, NHTSA did not stipulate what kinds of noises manufacturers chose to install in their vehicles.

Some automakers have already selected their sounds. Mercedes-Benz has an artificial humming sound picked out for its electric EQC lineup, while VW has said its compact ID.3 electric vehicles will come installed with a fake sound for low speeds when they hit showroom floors in 2020. Mercedes-AMG, the automaker’s performance brand, is working with rock band Linkin Park to find a more bass-slapping sound for its vehicles.

Some automakers are already exploring ways to make money off the absence of noise in EVs. Porsche is offering an interior $500 “Electric Sport Sound” in the configurator for its recently unveiled electric Taycan sports car, according to Electrek.

Other automakers, though, are looking for workarounds. Last year, The Verge reported that Ford was seeking a partial exemption for its lineup of police vehicles. The company is asking whether it could include an “off switch” — presumedly so law enforcement officials can use their EVs to sneak up on suspected criminals.

Updated September 17th, 9:50AM ET: Added statement from NHTSA spokesperson