Any talk of the future of cars and the rise of electric vehicles over the past few years will naturally focus on the green and clean aspect.

Recently, I also mentioned the possibility that this advancing automotive technology will also inevitably provide us with ever-quieter roads. Yet the other side of the coin – a side that any cyclist will be acutely aware of – is that people tend to walk out into a quiet road without looking or seemingly even thinking.

To counter this worryingly common human trait, from 1 July 2019 a new driving law comes into being. As of this day, all new electric and hybrid cars must produce a sound that allows pedestrians and cyclists to be aware of moving vehicles when not seeing them directly – just as it’s always been up until now with standard petrol and diesel vehicles. This is of course going to be a tremendous help to visually impaired pedestrians too.

The Acoustic Vehicle Alert System (AVAS) will be required to be active on vehicles up to a speed of 13mph at a decibel level of at least 56db but no more than 76db, keeping the noise levels comparatively low, but enough to be heard. As for speeds in excess of 13mph, the road noise produced by tyres is considered to be adequate.

AVAS will not just be a constant tone though; the system is required to be able to convey acceleration and slowing down. The idea is that those that need to be aware of the vehicle most do not have to go through too much of a new learning curve – we are all intrinsically aware from an early age what the sound of a speeding up engine is and any change in that might potentially cause confusion which may lead to accidents.

Electric Vehicles Must Now Produce a Sound by Law (2)

The AVAS will use volume and pitch shifting in an upward direction to denote acceleration and the opposite to denote deceleration. Sensors will be used to control the sound – a speed sensor along with a sensor directly in touch with the accelerator pedal.

The Acoustic Vehicle Alert System will only be required to be fitted to all new vehicles, and at present there is no requirement to retrofit the acoustic warning system to existing EVs.

Electric Vehicles Must Now Produce a Sound by Law (1)

Some basic rules exist though – you won’t be hearing a cacophony of music from all vehicles coming towards you and going past like ice cream vans. It sounds daft, but this is indeed part of the ruling; there is clearly no accounting for logic as regards what some might consider a ‘warning system’!

On a more serious note, it is expected that car manufacturers would no doubt see this an opportunity to advertise as such – to have a unique signature sound; so you knew when a BMW was about to pass for example. Therefore, rules are there to stop things getting out of hand.

Electric Vehicles Must Now Produce a Sound by Law (3)

Expanding the idea, internal sounds for the occupants of a vehicle are being explored in conjunction with external sounds. While the occupants of a family vehicle will no doubt enjoy the interior cabin silence of an EV, the more sporty electric car driver may want to replicate the sound of an engine within the cabin for a more all round sensory experience.

As Hugo Fastl, Professor at TUM Chair for Human-Machine Communication, says: we’ve spent time developing quieter and quieter cars, but now it seems we may – if we’re not careful – be looking at a future where the cars are just too quiet.

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