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'Sonic cannon' used to blast protesters' ears in Pittsburgh | Police in Pittsburgh, US, has shown
the usage of the 'sonic cannon', which is the latest innovation in crowd control,
by blasting the ears of protesters near the Group of 20 meeting of world economic
leaders. City officials said it was the first time such sound blasters, sometimes
called sound weapons, were used publicly. "There was an array of sound amplifiers
used during the demonstration," Lavonnie Bickerstaff of the Pittsburgh Bureau
of Police, told Live Science. "The Poconos police brought the long-range acoustic
device with them, but I don't know whether it was used," he said. The long range
acoustic device (LRAD) is designed for long-range communication and "unmistakable
warning," according to the American Technology Corporation, which develops the
instruments. "The LRAD basically is the ability to communicate clearly from 300
meters to 3 kilometers", said Robert Putnam of American Technology's media and
investor relations. "It's a focused output. What distinguishes it from other communications
tools out there is its ability to be heard clearly and intelligibly at a distance,
unlike bullhorns," he added. Its shrill warning tones can be heard at least 1,600
feet (500 meters) away and depending on the model of LRAD, it can blast a maximum
sound of 145 to 151 decibels - equal to a gunshot - within a 3-foot (one meter)
range, according to American Technology. But there is a volume knob, so its output
can be less than max, Putnam noted. On the decibel scale, an increase of 10 (say,
from 70 to 80) means that a sound is 10 times more intense. Normal traffic noise
can reach 85 decibels. Anything over 120 decibels is liable to be noticeably painful
for some individuals, and 150 decibels would hurt anyone's ears. Such sounds damage
small hair cells in the inner ear that convert sound energy into electrical signals
that travel to the brain. But, Putnam said that under normal circumstances, the
LRAD is not harmful. "There's no way it can hurt you unless you have the ability
to stand in front of it closely for several minutes," Putnam said. The instrument's
volume, along with its high-pitched tone, make for painfully loud sound frequencies
that are concentrated in a narrow beam and easily direct them at a target, not
unlike using a spotlight. |
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