The Long Range Acoustic Device (LRAD) is a distance hailing device and non-lethal crowd control weapon developed by LRAD Corporation to send messages, warnings, and harmful, pain inducing tones over longer distances than normal loudspeakers.
According to the manufacturer's specifications, the systems weigh from 15 to 320 pounds (6.8 to 150 kg) and can emit sound in a 30° beam at 2.5 kHz.[1]
LRAD systems are used by maritime, law enforcement, military and commercial security companies to send instructions and warnings over distances, and to force compliance. LRAD is also used to deter wildlife from airport runways, wind and solar farms, nuclear power facilities, mining and agricultural operations and other industrial facilities.
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The parameter "ka", which is the wave number multiplied by the speaker radius, is often used to characterize sound source directivity. For this source, ka=19 at 2.5 kHz, and according to the LRAD data sheet, the beam angle of about 30 degrees total is precisely what is predicted for a regular loudspeaker.[2]
Small spherical "point-source" acoustic devices follow the known inverse square law, which predicts the loss of 6 dB per doubling of distance from the source, solely due to geometric spreading. Large speakers (or large arrays), such as these mentioned above or those commonly used in concert halls, etc., produce less attenuation with distance in the nearfield, typically 3–4 dB per doubling of distance from the source. The larger the speaker, and the higher the frequency, the longer the effective nearfield. Devices like this generally have nearfields of only a few meters. However, sound radiated from an infinite plane source is not attenuated due to geometric spreading, but is affected by other sound propagation effects.
LRAD Corporation was formerly named American Technology Corporation. Carl Gruenler, former vice president of military and government operations for American Technology Corporation said that being within 100 metres (330 ft) of the LRAD is extremely painful, and that it was designed for use in short bursts at 300 metres (980 ft), to give targeted people a headache. He said that "you definitely don't want to be" within 100 m; that the device will cause permanent auditory damage.[3] LRAD officials deny such common uses, claiming that the device is not a weapon, rather it is a "directed-sound communications system", and that it can damage hearing at 15 metres (49 ft).[4] American comedian Jon Stewart lampooned the supposed harmful effect of LRAD’s deterrent tone on The Daily Show with Jon Stewart by putting his fingers in his ears.[5]
The LRAD device was on hand at protests of the 2004 Republican National Convention in New York City[6] but not used; it was extensively used against opposition protesters in Tbilisi, Georgia, in November 2007.[7]
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 Tiananmen Square protests of 1989.
Local residents of Dusit in Bangkok witnessed it in use during protests of Triumph factory employees against dismissals on August 28, 2009.[8] The LRAD was used for the first time in the United States in Pittsburgh during the time of the G20 summit on September 24–25th, 2009.[9][10] Pittsburgh police again utilized LRAD as a precautionary measure to prevent unruly crowds from getting out of control following the 2011 Super Bowl. LRAD systems were also purchased by Toronto Police for the 2010 G20 summit.
In 2009, the government of Honduras used it on at least two occasions, on September 22 and 25, to communicate to those seeking refuge in the Brazilian embassy. In addition to embassy staff, these included the deposed president of Honduras, Manuel Zelaya, his family, and some supporters and journalists.
LRAD was also used against college students in the city of Macomb, Illinois at the Wheeler Block Party at Western Illinois University ("WIU")[11] on May 1, 2011.[1]
LRAD was reportedly[12] used by the Oakland Police Department during the clearance of the Occupy Oakland encampment on the morning of 25 October 2011.
The Polish Police acquired LRAD units in December 2010 and used them to communicate with protesters during the 11 November 2011 riots in Warsaw. [13]
LRAD was present, but not used, when the New York City Police department cleared Occupy Wall Street protestors from Zuccotti Park on the morning of 15 November 2011.[2]
LRAD was present, but not used, when the Boston Police Department cleared Occupy Boston protestors from Dewey Square on the morning of 10 December 2011. [3]
On November 5, 2005, the luxury cruise ship Seabourn Spirit employed an LRAD while repelling pirates who attacked the vessel with rocket-propelled grenades about 115 km off the coast of Somalia.[14][15] The effectiveness of this device during the attack is not completely clear, but the pirates did not succeed in boarding the vessel and eventually fled.
The Liberian vessel MV Biscaglia was attacked on November 28, 2008. The security detachment aboard Biscaglia claimed to have used an LRAD device in an effort to repel attackers armed with assault rifles and rocket-propelled grenades. Following a one-sided shootout, the ship was seized and the unarmed security contractors abandoned ship leaving the ship and crew to the pirates.[16] The incident caused the usefulness of LRADs to be called into question by Lloyd's List,[17] In January 2011, the Spirit of Adventure, a cruise ship sailing through the Indian Ocean, deployed a LRAD system as part of its defensive measures when being pursued by pirates.[4]
In February 2009, the Japanese whaling fleet operating in Antarctic waters near Australia installed LRADs on their vessels. The device was used against activists of the Sea Shepherd Conservation Society after they harassed the factory ship.[18] The Japanese fleet later escalated the use of LRAD, deploying it against a Sea Shepherd helicopter carrying a camera crew.[19][20] Sea Shepherd noted that they had an LRAD of their own, but as of early 2010, had not put it into use[21] other than to play a recording of "Ride of the Valkyries" in the manner of attacking U.S. Army helicopters depicted in the 1979 film Apocalypse Now.[22]