A Loud Tone Played Before Impact May Reduce Whiplash
NEW
YORK (Reuters Health) - If a vehicle could emit a loud tone just before
a crash, the sound might startle the occupants and induce muscle
reactions that limit the extent of injury, a new study suggests.
A
105 decibel tone emitted just 205 ms before impact appears to reduce
the reflexive responses of muscles in the head and neck that ordinarily
activate during whiplash, according to research published online August 7
in The Spine Journal.
The results are too preliminary to suggest
that a pre-impact tone emitter should become a standard safety device,
but the findings merit research in the real world, according to Gunter
Siegmund, Director of Research at MEA Forensic Engineers and Scientists
in Richmond, BC, Canada, who led the study.
Siegmund told Reuters
Health by email, "We know that startle forms part of the neuromuscular
response during the kinds of vehicle impacts that can cause whiplash
injury. We also know that a loud pre-impact sound can attenuate the
startle portion of the response and reduce neck muscle activation levels
and head/neck motion. While it seems reasonable to postulate that
reduced forces and motion will reduce the likelihood of tissue injury in
some individuals, we don't yet know whether this will decrease the rate
of actual whiplash injuries in the field."
To study the effect of
the tones, 12 volunteers sat in a test sled made up like the driver's
seat of a Honda Accord. They each underwent three simulated rear-end
crashes either with a tone or without. In each simulation the sled
accelerated suddenly at a maximum speed of 19.5 m/s2.
The
volunteers were fitted with electromyographic electrodes, both on the
surface and inserted into their muscles. They were also fitted with
accelerometers to record the motion of the head and torso.
The
tone appears to have significantly reduced the amplitude of the C6
multifidus muscle by 42% and the C4 paraspinal muscles by 30%.
Changes in amplitudes in the C4 multifidus and sternocleidomastoid muscles were not statistically significant.
The
accelerometers recorded decreased head retraction after the tone by
3.3mm, which was a 9% difference. Peak head angular acceleration in
extension and head extension angle were also improved after the tone,
while a difference in peak horizontal head acceleration was not found to
be statistically significant.
Further testing may require the
installation of devices into vehicles because standard crash-test
dummies will not be adequate to evaluate muscle responses, Siegmund
said.
"Should manufacturers consider including this as a safety
feature? I think so," he said. "The technology to detect imminent
collisions already exists in some vehicles, and virtually all modern
vehicles have speakers that can play a loud tone. Therefore the
incremental cost of including this safety system may be relatively low.
Two companies have already approached us to commercialize the
technology, but I don't know what if anything they are doing with it."
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