Due to recently voiced concerns over pedestrian and cyclist safety that hybrids can sneak up unexpectedly and hit them, companies are working on external sound systems that would make engine-type noises. Lotus Engineering on Tuesday announced it has a working prototype of such a system on a Toyota Prius .
The system produces a synthesized external engine sound when the vehicle is in motion. Such systems may soon be mandated for quiet-running hybrid vehicles by the government, with Lotus hoping its work is not for naught.
Lotus’ Safe & Sound Hybrid technology demonstrator was installed in a standard Toyota Prius , and represents an application of the company’s Sound Synthesis tech, which Lotus uses for active road noise cancellation in the interior of vehicles. The system takes a road speed signal and, provided the car is in quiet, electric operation mode only, it will send a series of engine sounds to the waterproof loudspeakers located beside the radiator. The emitted sound is appropriate to the speed of the car in pitch and frequency, giving hearing or visually impaired pedestrians an idea of how far and how fast the vehicle is moving. When the hybrid fires up the gasoline engine, the system seamlessly stops emitting the sound and goes back on when the engine is turned off automatically. Lotus claims little of the synthetic sound makes it into the vehicle’s interior.
