SOUND ENGINEERING
(see box). One of the most important next
steps was the launch of its broadband
sounder, or BBS, in 2000, also for
reversing vehicles. In contrast to a singlefrequency
digital tone, it emits a ‘white
noise’ over a number of frequencies. This
is said to be not only more pleasant, but
also, crucially, more directional. Brigade
would demonstrate this by placing a
blindfolded volunteer in the midst of a
circle of eight speakers, one of which
randomly made either a tonal or broadband
alarm. The volunteer’s job was to turn to
face the speaker that had sounded, so
they could catch the ball that was thrown
at them. Or not. “If it’s tonal, there was
every chance they would be 180 degrees
out,” recalls Nevard.
MEETING EXPECTATIONS
Designing an alarm sadly isn’t only a
matter of being audible and directional;
it has to take into account the hearer’s
psychology as well. Nevard points out:
“People look for the wrong thing; so
it’s important that it’s a sound that
they recognise. We did some work with
the sound of cows. That’s great for
getting people’s attention in an urban
environment; you don’t expect to see a
herd of cattle in Oxford Street. But the
problem is that they don’t look at the
vehicle that’s generating the sound. They
look past it, because they are looking for
the cows.”
Lacking the growl of an internal
combustion engine, quiet vehicles pose
the greatest risk to other road users when
they are about to move off. A bus driver, for
example, cannot move away from the kerb
until the road is clear; and without some
kind of alarm, those who are not paying
attention will not know to get out of the way.
So Brigade’s Quiet Vehicle Sounder
product starts emitting sound as soon
as the vehicle’s driver releases the
handbrake, and it continues to do so
until the vehicle reaches 20mph, when it
switches off. At that speed, the crunch of
its tyres on the tarmac and whoosh of the
air it displaces will be loud enough to warn
other road users of the vehicle’s approach.
It uses white noise, like the reversing
alarm. But to avoid any confusion of the
listener, the QVS sounds continuously,
while the reversing alarm is interrupted
with pauses lasting a fraction of a second.
Of course, the faster the vehicle goes,
the less time there is to get out of its way.
The regulations recognise this inevitable
fact by requiring the sounder volume to
ramp up with velocity. And that’s not all;
the sound also changes frequency with
increasing speed, helping provide another
auditory clue about speed, just as a
labouring engine would. Brigade’s QVS
emitter produces a sound that includes
four frequencies: two that move in pitch
and two that are xed, for blending.
In developing the QVS product, Brigade
tested some 80 sound pro les, all of
which met the minimum criteria, with a
panel of testers chosen to be diverse in
ethnicity, age and sex, to make sure it
Vehicle alarms aim to make sound only
where it is needed
would work for any pedestrian in an urban
environment. It was also tested on real
roads in both North America and in Europe,
as the road surfaces differ greatly.
Nevard says that the rst step was
static testing, asking its panel subjects
which of the sounds generated in a
static trial they like or dislike, and why.
Those results led to a trials of a smaller
number on actual vehicles. Those tests,
in turn, were honed down again, and the
frequencies and how they moved on a
particular vehicle were ne-tuned. Then,
nally, a particular sound was tried out on
a range of different vehicles in different
environments.
Real-world trials started in late 2017.
They included trials on vans at Portsmouth
Docks, where the Navy was concerned
about the welfare of sailors off of long
tours of duty at sea, who take little notice
of vehicles around them. BAE Systems,
via Lex Autolease, tted the sounders
to Nissan e-NV200 vans. Other triallists
include Birmingham University, road
repairer Conway and parcel rm Hermes.
The sounders – which are being tted
as standard to Jaguar Land Rover’s I-Pace
sport utility vehicle, are also suitable for
electric pallet trucks, small diggers, local
delivery vehicles and buses and coaches.
European car and truck brand Renault and
truck brand IVECO have elected to design
their own systems. But the more niche
markets, such as bus and coach, are of
most interest to Brigade.
The device itself consists of a 120mm
by 115mm by 130mm speaker inside a
waterproof (IP68) housing to be mounted
at the front left-hand (offside) of the
vehicle, ideally behind a front grille that
allows the sound to pass. Aiming the
speaker at the target audience helps
maximise the chances it will be heard,
while reducing its effect in generating
noise pollution. “You don’t need to hear
it outside of the danger zone,” states
Bowen. The speaker is controlled by an
ECU, to be mounted inside, that takes
an input from the vehicle’s tachograph
(in commercial vehicles) or its CAN-Bus
electronic control system. Installation
takes about a day, and Brigade engineers
usually train the trainers.
Regardless, the largest amount of
education required is of the customer
markets to which Brigade is selling.
Nevard concludes: “The rst time that you
bring something like this in, people make
some very wild assumptions.”
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