The huge horn
pictured above is one of four giant acoustic orifices at the ESA’s LargeEuropean Acoustic Facility in Noordwijk, the Netherlands.
Rather than killing humans, though, the horns are actually for testing
satellites — to see if they can withstand the noise of a rocket launch. As you
may know, the Space Shuttle’s Mobile Launch Platform used to dump 300,000
gallons of water onto the platform during launch, to absorb the intense
acoustic energy that would otherwise damage the Shuttle.
The ESA’s horns are
essentially giant air horns, using nitrogen gas to produce sounds as loud as
154 decibels. Can sound kill you? The short answer is “yes” — and, rather shockingly, the European Space Agency says that it now has such a sonic weapon in its arsenal that, if it was so inclined, could kill you. For the long answer, read on.
The question is, is
154 decibels enough to kill you? In all honesty, probably not — unless,
perhaps, you were stuck with your head inside the horn for a prolonged period.
150 decibels is usually considered enough to burst your eardrums, but the
threshold for death is usually pegged at around 185-200 dB. A passenger car
driving by at 25 feet is about 60 dB, being next to a jackhammer or lawn mower
is around 100 dB, a nearby chainsaw is 120 dB. Generally, 150 dB (eardrum
rupture) is only achieved if you stand really close to a jet aircraft during
take-off or you’re near an explosive blast.
If you actually
wanted to intentionally kill someone with a sonic weapon, there isn’t a
whole lot of research on how you would actually go about doing it. The general
consensus is that a loud enough sound could cause an air embolism in your
lungs, which then travels to your heart and kills you.
Alternatively, your
lungs might simply burst from the increased air pressure. (Acoustic energy is
just waves of varying sound pressure; the higher the energy, the higher the
pressure, the louder the sound.) In some cases, where there’s some kind of
underlying physical weakness, loud sounds might cause a seizure or heart attack
— but there’s very little evidence to suggest this.
Perhaps more
significantly, though, it’s important to note that a sonic weapon doesn’t have
to be lethal or incredibly loud to be effective.
High-intensity ultrasonic sound (generally anything above 20KHz) can cause
physical damage. Some very low frequencies (infra sound) can apparently cause
your eyeballs to vibrate, making it very hard to see. Targeted “sonic bullets”
that cause localized pain (or simply burst your eardrums) is probably enough to
immobilize most non-action-hero humans.
So, there you have
it: Sound can kill you, but not in the
standing in front of a giant speaker stack at a gig way that you were probably
thinking. Unless you’re in an explosive blast (in which case you’d have other
concerns, too), or you’re the victim of military testing of sonic weapons, the
worst that will probably happen is that your eardrums would burst.
1 comment:
really very nice info
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