Since 1 July 2019, it has been mandatory to install a warning sound generator in electric vehicles in Europe. This is due to a new EU directive which stipulates that initially in newly certificated hybrid, electric and fuel cell vehicles, including trucks and buses, the acoustic vehicle alerting system (AVAS) must be installed for the protection of other road users.
In the EU, the acoustic warning is mandatory up to a speed of 20 km/h and the directive formulates the parameters for how an AVAS warning may and may not sound in great detail. This applies, for example, to the minimum and maximum sound volume, and to certain sound components.
It is subject to these and many other regulations that the sound experts of the acoustic test facility at the Mercedes-Benz Technology Centre (MTC) in Sindelfingen are working on giving a voice to the electrified Mercedes. Special microphones in the exterior sound testing facilities are used to develop an individually configured e-sound for each electric model.
Simulations, measurements, evaluations and detailed improvements continue until the result is perfect. During the subsequent test drives, there is a particularly sensitive passenger on board – the artificial head. This registers the tiniest noises and comes impressively close to human hearing.
The Mercedes-Benz AVAS sound differs only slightly in the EU, Japan and China, and there are other requirements for the USA, such as with regard to the sound volume.
Furthermore, the stationary vehicle must already generate a sound when a gear is engaged, becoming louder up to 30 km/h. Switching off the AVAS by the customer is prohibited in almost all countries.