Noise to the outside, silence inwards

October 04, 2012 // By Christoph Hammerschmidt
A major European automaker will integrate the HALOsonic External Sound Synthesis (ESS) equipment from infotainment group Harman in a line of plug-in hybrid vehicles. HALOsonic generates sound outside the vehicle in order to provide an acoustic warning to pedestrians - electric and hybrid vehicles are extremely silent, in particular at low speeds.

Hybrids and electric vehicles present a safety concern at low speed as they often cannot be heard and recognized. HALOsonic ESS generates a synthesized sound, dependent on speed and direction, and projects it from an exterior mounted speaker, giving an early identifiable warning to pedestrians that the car is approaching. The sound is projected only in the direction of travel, fading away almost instantly once the vehicle has passed. A synthetic engine 'idle' sound is also produced when the vehicle is switched on and placed in gear.

Several countries such as USA, Japan and parts of Europe have either implemented or are currently reviewing legislation to state that hybrid and electric vehicles must emit a recognizable sound above a minimum noise level to help improve pedestrian safety.

Vehicle manufacturers are striving to meet new environmental and emission standards by a variety of means including, for instance, lowering vehicle weight by reducing the amount of noise-dampening insulation in a car’s headliner. In doing so, cabin noise often increases. Harman’s HALOsonic can produce sounds not only external to the vehicle, but generate noise-cancelling sound inside the vehicle that helps meet environmental goals while increasing driver comfort.

The company did not elaborate as to the availability of the technology for the public.