In brief: One of the identifying features of electric cars is that they run almost silent, especially when compared to their traditional fossil fuel-powered counterparts. But this is changing in the European Union, where a rule requires new EVs to include a noise-emitting device.

The EU rule, which came into force today, states that all new types of four-wheeled electric vehicles must be fitted with an Acoustic Vehicle Alert System, or AVAS, which makes a noise like a standard engine when the vehicle drops below 12mph. You can hear it yourself in the clip below.

The BBC reports that while the charity Guide Dogs welcomed the change, it said the vehicles should make sounds at all speeds.

"This new requirement will give pedestrians added confidence when crossing the road," said the UK's Roads Minister, Michael Ellis.

The noise-makers activate at 12mph and lower because the EU says cars are most likely to be near pedestrians when driving slowly or backing up. Interestingly, drivers will be able to deactivate the devices if they believe it is necessary.

From 2021, all new electric cars must include the noisemakers, not just new models. It's thought that EVs already on the roads will be retrofitted with the devices.

Back in 2017, the UK announced that it would be following the lead of several other European nations by banning the sale of fossil fuel-powered vehicles as a way of dealing with airborne pollution. The plan is set to come into effect from 2040.