Owners of electric cars should be able to choose the noise their vehicle makes to alert pedestrians, says a US road safety body.
The National Highway Traffic Safety Administration (NHTSA) says car makers may give several sound choices to owners of the "quiet cars".
Vehicles must generate the noise when travelling at less than 30 kph (19mph).
The NHTSA is also asking the public how many types of sounds cars can make, and how loud they can be.
