Toyota now sells an accessory for its Prius hybrid car that generates synthesized engine sounds to alert pedestrians to the presence of the car when it is running silently on its electric motor.

Electric cars produce very little sound at speeds under 20mph and if their number increases there is concern that pedestrians and cyclists will be at risk. In a study conducted by the University of California, pedestrians heard a petrol-engined vehicle moving at 5 miles per hour three seconds before it reached them – by the time they heard an electric car, it had already passed by.

The sound of silence

New laws in Japan for hybrid and near-silent vehicles have prompted Toyota the device for retrofitting to its third-generation Prius.

Toyota describes the new electronic sound as “aimed to alert but not annoy”. It is emitted when the Prius is being driven as an electric vehicle at speeds up to 15mph and would otherwise be near silent.

Europe law may soon follow suit, but there is nothing to say that artificial soundtracks for electric vehicles need sound like a petrol engine. The safety laws may result in cars that sing songs, chirrup like a bird or even make the thumping noise of a pod racer from Star Wars.

Source: http://www.eta.co.uk/2010/09/02/toyota-offers-synthesized-engine-sounds-prius