Electric cars make very little noise when travelling at slow speeds. Whilst this may provide a welcome break from incessant traffic noise, it has also caused significantly safety concerns as electric vehicles grow in popularity. Research suggests that electric cars are 40% more likely to hit pedestrians than conventional vehicles. As of July 2019, all new electric and hybrid cars in Europe will have to emit sound when travelling at low speeds.
The issue has prompted huge debate about what form the designed sound should take. US legislation originally looked set to enforce sounds with a similar frequency to ambulance sirens. The agreed European standard is a mix of tonal sounds and white noise, which will cut out once the vehicle speed reaches 20kph.
Chris Hanson-Abbott of Brigade Electronics has advised the UN on sonic safety standards. “The object is to have warnings which are audible but which are not the least bit environmentally disturbing”, he said. Hanson-Abbott explained that the benefit of white noise is its pleasant ambience and, crucially, the fact that its directional source is instantly recognisable. By contrast, it is harder to judge the source of tonal sounds, which often bounce off hard surfaces.
For some automobile companies, motor sound is synonymous with the brand itself. Harley Davidsson once attempted to trademark the sound of their engine. It remains to be heard how manufacturers may utilise audio branding in tandem with safety legislation to differentiate their vehicles.
In 2013, technology company Semcon proposed an ambitious Sonic Movement concept which highlighted the opportunity for intelligent, responsive automobile sound. Their project included vehicle noise that adjusts to its surrounding environment, to ensure that sound is audible but never a nuisance. They also proposed sound that synchronises with surrounding vehicles – imagine, for example, a tribe of harmonious BMW’s pulling up to a set of traffic lights.