posted on Sep, 25 2009 @ 01:27 PM
reply to post by mr-lizard
LRAD = Long Range Acoustic Device
The Long Range Acoustic Device (LRAD) is a crowd-control and hailing device developed by American Technology Corporation.
According to the manufacturer's specifications, the equipment weighs 45 pounds (20 kg) and can emit sound in a 30° beam (only at high frequency, 2.5
kHz) from a device 83 centimetres (33 in) in diameter. At maximum level, it can emit a warning tone that is 146 dBSPL (1,000 W/m²) at 1 metre, a
level that is capable of permanently damaging hearing, and higher than the normal human threshold of pain (120–140 dB). The maximum usable design
range extends to 300 metres. At 300 metres, the warning tone (measured) is less than 90 dB. The warning tone is a high-pitched shrill tone similar to
that of a smoke detector.
There appears to be some disagreement over these specifications, as some[who?] have reported measurements that differ from the manufacturer's
specifications, and show reduced output with a less directive beam.
Carl Gruenler, former Vice President of Military and Government Operations for American Technology Corp. (and who now runs a company making a
competing device), says that being within 90 metres (98 yd) of the device is extremely painful, but its use should be limited to 270 metres (300 yd)
to be effectively used. He concedes that the device is powerful enough to cause permanent auditory damage, but that it is only meant to be used for a
few seconds at a time.
Countermeasures may include the use of passive hearing protection (earplugs, headsets), which may bring the sound down to ineffective levels. In
addition, sound could be reflected from a solid surface, and redirected back to the originator.
edit to add
The magazine Foreign Policy has revealed that LRADs have been sold to the government of the People's Republic of China. American companies have been
banned from selling arms to China since the 1989 Tiananmen Square Massacre, but the LRAD is described by ATC as a “directed-sounds communications
[edit on 25-9-2009 by MikeNice81]