Cars being driven on battery power represent a danger to pedestrians—especially the blind and visually impaired—because the vehicles produce no engine noise. To mitigate that danger, NHTSA (U.S. National Highway Traffic Safety Administration) will require that electrified vehicles emit sound at low speed (less than 18 mph). The regulation is only a proposal at this time, and the agency will seek public comment once it is published in the Federal Register (FR). Publication in the FR is when a proposal becomes official, and it typically follows by a week or so a less formal announcement (press release and unofficial version of the proposal) by NHTSA of its intentions on a particular subject. As proposed unofficially by NHTSA on Jan. 7, this rule would spell out minimum requirements for sound, but give vehicle makers flexibility in engineering it. An act of Congress requires that the agency issue a final sound regulation no later than Jan. 4, 2014, and that it be phased in over several years.