After decades of trying make cars quieter, manufacturers of electric cars are working to bring back the decibels.
Concerned that virtually inaudible electric cars could turn into silent killers for pedestrians, Nissan engineers are developing an artificial sound for the company's forthcoming electric vehicle, the Leaf.
Nissan have so far developed possible sounds such as the chime, the melody and what they describe as a 'futuristic whirr'. The company has declined to release the audio.
Tesla keeps quiet
However, officials at electric sports car manufacturer, Tesla, say they have no intention of implementing 'fake noises' in their vehicles.
Tesla spokeswoman Rachel Konrad said: 'We have delivered more than 700 cars, and our customers overwhelmingly say the relative quiet of the powertrain is one of the most appealing aspects of the car.
'Thanks to widespread electric vehicle adoption, we will all enjoy far less noise pollution in the future.'
Study shows increased risk
An American report, covering 8000 hybrid vehicles and 600,000 conventionally powered vehicles, suggests that during low-speed manoeuvres, such as reversing and turning, hybrids are 50% more likely to be involved in an accident with a pedestrian.