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External sound technology
enhances pedestrian safety for
quiet vehicles
Lotus Engineering has developed
technologies to synthesise
external sound on electric and
hybrid vehicles to counteract
the growing concern these
‘quiet’ vehicles pose to
pedestrians and cyclists. A
simulation of a real engine
sound is used on the ‘Safe &
Sound’ Hybrid technology
demonstrator vehicle, making it
instantly recognisable that the
vehicle is in motion.
Electric and hybrid vehicles, a
favourite choice of the
environmentally conscientious
have recently come in for
criticism from blind and
partially sighted people. Due to
the almost silent operation of
hybrid vehicles at slower speed
when running on electric power,
the independent travel of the
blind and partially sighted may
be put at risk as they cannot
hear these quiet vehicles as
they approach, making crossing a
road or walking through a car
park hazardous.
Mike Kimberley, Chief Executive
Officer of Group Lotus plc said
“The increased acceptance of
greener vehicles such as hybrid
and electric vehicles is to be
encouraged; they have an
important role in improving fuel
economy and reducing emissions.
Our advanced external sound
synthesis technology increases
pedestrian safety, while
retaining the car’s
environmental benefits. We hope
that legislators introduce
minimum noise requirements for
vehicles to encourage the
adoption of technologies, such
as ours, which will ultimately
increase pedestrian safety.”
Clive Wood, Transport Policy
Officer at The Guide Dogs for
the Blind Association said:
“Blind and partially sighted
people use the noise of oncoming
traffic as a cue for when it is
safe to cross a road – if a
‘quiet’ hybrid electric vehicle
is approaching then they will no
longer have this cue and are
immediately put at risk.
The Lotus ‘Safe & Sound’ Hybrid
technology demonstrator uses a
standard Toyota Prius, one of
the highest volume and most
advanced hybrid vehicles to
demonstrate the sound synthesis
application and compensate for
the lack of engine noise emitted
by the vehicle when running on
an electric motor. What has
resulted is the same
environmentally conscious hybrid
vehicle, without the potential
risk to pedestrians and
cyclists.
The solution that Lotus has
devised is a novel reapplication
and development of its Sound
Synthesis technology. This is a
part of the Lotus suite of
patented active noise
technologies which comprise
three main systems, Active Road
Noise Cancellation, Engine Order
Cancellation and Sound
Synthesis.
In
order to generate the engine
sound, recordings of a suitable
donor engine were made and
analysed to establish the
characteristic frequencies at
different engine speeds. These
frequencies are then entered
into the synthesis controller in
the form of a ‘voice’ which
outputs the sound through an
amplifier and out through the
loudspeakers. |
