Automakers are looking at giving their electric cars futuristic sounds to ensure that the vehicles don't pose a danger to pedestrians who cannot hear them coming.
Unlike gasoline or diesel cars, EVs are almost silent when they start and accelerate to cruising speeds. Pedestrian safety lobbyists and organizations for the blind worldwide are campaigning for legislation to ensure EVs are given a unique sound that can be heard by people outside the car.
Nissan's Leaf battery powered compact hatchback emits a noise that can be described as a cross between a small jet plane and a monorail. The sound was developed with input from the U.S.-based National Federation for the Blind and the Detroit Institute of Ophthalmology, which Nissan said helped configure the final specifications.
However, the development of sound-emitting devices remains at the very early stages, Tom F. Smith, chief marketing manager for the Leaf told Automotive News Europe. “There is going to be a learning curve, no doubt,” Smith said.
Audi's acoustics experts are working to create a futuristic engine note for the brand's electric cars and are drawing inspiration from science fiction. The German premium brand is developing a range of electric cars that will be sold under the badge E-tron.
Christian Schueller, Audi's head of brand development, said the automaker is avoiding the obvious approach of working with the familiar sound of a combustion engine, because "we want to underscore that an electric or hybrid Audi is an innovative product."
Ralf Kunkel, Audi's head of acoustics, said: “The sounds used for space ships in films are reminiscent of car sounds, yet are also very different, making this a rather interesting approach."
Audi said its E-tron cars will not sound like a jet airplane or a space ship from a science fiction film any time soon. “But the sound will be new and unusual. The Audi RSQ from the 2004 Hollywood film I, Robot gives an indication of how an Audi might sound in the future,” the company said.
Danger in the parking lot
Vincent Roussarie, a psycho-acoustic engineer for PSA/Peugeot-Citroen, said standards for maximum noise levels have long been established, but finding new norms for minimum decibel levels poses unique challenges. “It can't be just any noise, but one that effectively warns pedestrians of the danger,” he said. “And to start doing that, it is first necessary to evaluate what the risks and dangers are [that silent EVs pose].”
EVs are especially dangerous to pedestrians during the first seconds when the vehicles move from a standstill, for example when an EV leaves a parking place at grocery store lot, Roussarie said
“You might think the danger merely involves cars already in motion that are headed in the pedestrian's direction on a road or street, but a vehicle that accelerates from a standstill three or four meters from the pedestrian represents a greater danger since the car makes absolutely no noise then,” he said.