Since last July, new types of electric, hybrid, and fuel cell vehicles in Europe—usually silent—have been required to make noise with what’s officially called an AVAS, for Acoustic Vehicle Alerting System, to protect road users such as pedestrians, cyclists, and the visually impaired. Similar regulations apply or are under development in the U.S. and China. Hella have devised a compliant acoustic warning system for use in passenger cars, commercial vehicles and buses.
Hella’s AVAS gives vehicles with noiseless powertrains a sound similar to a conventional internal combustion engine. This enables road users to detect approaching vehicles they may not be able to see. AVAS will be presented by Hella for the first time at the Busworld trade fair starting on 18 October in Brussels.
At speeds below 20 km/h, the AVAS simulates a noise
that rises when the speed increases. The AVAS also automatically generates an
acoustic signal when reversing. At speeds above 20 km/h, the simulated engine
sound is silenced as the sound of the tyres rolling on the road is loud enough.
A video posted online demonstrates
Mercedes’ AVAS for Europe and for the USA in comparison to petrol-powered cars’
noise signatures.
The regulations specify minimum sound pressure levels and frequency distribution and content of the
noise, and a standard sound is stored onboard Hella’s AVAS unit. But there’s
plenty of flexibility in exactly what the noise sounds like—just as combustion
vehicles sound different depending on characteristics of the engine,
transmission, and exhaust system—so brand- or model-specific AVAS sounds can be
developed and deployed.
