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Article: Lotus ‘Safe & Sound’ system makes hybrid,electric vehicles audible

August 12, 2008 • Darrell Shandrow Hilliker

We are relieved to learn that a solution now exists to the safety concerns
posed by electric and hybrid vehicles to blind and visually impaired
pedestrians. It is now up to those of us in the blind community to insist on
the implementation of this or a similar solution on all such autos. Now that
a concrete solution is available, we can act to ensure our safety. States
could enact legislation requiring the installation of an audible noise
making device on these vehicles in order to pass DMV inspections. The auto
insurance industry could also require such an installation on a car as a
condition of selling a policy to the driver.
The article entitled Lotus 'Safe & Sound' system makes hybrid, electric
vehicles audible can be found at
www.cnet.com.au/cartech/cars/0,2000438541,339291235,00.htm

Due to the almost silent operation of hybrid and electric vehicles running
on electric power at slow speeds, blind and partially sighted pedestrians
may be at risk while crossing roads or walking through parking lots since
they cannot hear the vehicles as they approach.

Lotus Engineering, a name most commonly associated with lightweight sports
cars, has announced that it has developed a system to synthesise external
sound on electric and hybrid vehicles to make them more audible to
pedestrians and cyclists. A simulation of a real engine sound is used on
Lotus' Safe & Sound
Hybrid technology demonstrator vehicle, making it instantly recognisable
that the vehicle is in motion.

The demonstration vehicle is a Toyota Prius equipped to demonstrate the
sound synthesis application. The solution Lotus has devised is a
re-application and development of its Sound Synthesis technology, a suite of
technologies originally designed to reduce the amount of cabin noise in a
conventional motor vehicle by using active sound cancellation.

An artificial engine sound is played through a waterproof loudspeaker in the
car's nose, compensating for the lack of engine noise emitted by the vehicle
when running on an electric motor. Because it's just a speaker, Lotus can
make any sound they want, but they've stuck to using an existing engine
sound
that makes the vehicle instantly recognisable, with the pitch and frequency
helping to identify its distance and speed. Front-facing speakers mean that
once the vehicle has passed, the sound is no longer heard.

In electric-only vehicles, the system is always on, but for hybrids the
system only operates when the vehicle is using electric power. If the
hybrid's engine starts operating – either at higher speeds, higher throttle
demands, or lower battery levels – the control system automatically stops
the external synthesis.
It is all completely automatic and, according to Lotus, the driver hears
almost none of the additional sound.

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