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The Long Range Acoustic Device (LRAD), also known as a sound cannon, is an acoustic hailing device and sonic weapon developed by LRAD Corporation to send messages, warnings, and harmful, pain inducing tones over longer distances than normal loudspeakers. LRAD systems have been used to counter piracy, as non-lethal crowd control weapons, and as communication devices.
According to the manufacturer's specifications, the systems weigh from 15 to 320 pounds (6.8 to 145.1 kg) and can emit sound in a 30° beam at 2.5 kHz.
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.
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.
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, have an interference pattern in the nearfield which produces peaks 6 dB higher than the output pressure and nulls where the pressure is essentially zero. The larger the speaker, and the higher the frequency, the longer the effective nearfield. The nearfield for this device is approximately 8m.
LRAD Corporation was formerly named American Technology Corporation. In 2004, Carl Gruenler, a 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; and, that the device will cause permanent auditory damage. LRAD officials deny such common uses, claiming that the device is not a weapon, rather it is a "directed sound communications system." After LRAD devices were used during the 2009 G-20 Pittsburgh summit, 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.
In 2009, the government of Honduras used LRAD on at least two occasions, on September 22 and 25, on 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. In a photo, there are two LRAD models, the LRAD 1000 (or 1000X or 1000Xi) and the LRAD 100X. Israel was accused of supplying these devices,
Israel's Ministry of Defense ordered LRADs in June 2011.
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. Two days later it was reportedly used briefly against Occupy Wall Street protesters.
LRAD was present, but not used because of current legal regulations during protests in Poland, including Million Marijuana March 2011 and Marsz Niepodległości (National Independence Day March) 2011 and 2012. Lacking a way to utilize the LRADs purchased to their full potential sparked an investigation suspecting corruption behind their acquisition. National Police Headquarters spokesman Mariusz Sokolowski defended the purchase of LRAD. He also stressed that the police decided to make this investment because, "We needed good sound reinforcement equipment. With numerous demonstrations and gatherings, police need a public address system that allows you to reach thousands of people."
LRAD was deployed during a NATO march on May 20, 2012 in Chicago, Illinois at Michigan Ave. & Cermack.
A portable LRAD was used in an unsuccessful attempt to disperse protesters in the capitol building in Madison, Wisconsin on July 18, 2013. The same LRAD was used by police to issue a warning before subsequently arresting several protesters on August 13, 2013.
The Salisbury, MD Police Department acquired an LRAD in October 2013 with proceeds from their speed cameras.
The Hong Kong Police Force acquired four LRADs to convey important messages over a long range in a noisy environment, in a bid to preserve public safety, public order and prevent injury to life and property.
17 January 2014 an LRAD was used by police against protesters in Barcelona, Spain. 
18 July 2014 an LRAD was used by police against people protesting mass water shut-offs in the city of Detroit. 
13, 18 August 2014 St. Louis County police used LRAD against protestors demonstrating the police shooting of Michael Brown in Ferguson, Missouri. Amnesty International criticized the use of LRAD against protesters and members of their delegation at Ferguson, who “reported feeling nauseous from the noise”, and that “LRADs can pose a serious health risks which range from temporary pain, loss of balance and eardrum rupture, to permanent hearing damage.”
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. 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. The incident caused the usefulness of LRADs to be called into question by Lloyd's List. In August 2013, Carl "Rocky" Mason, one of the three members of the security attachment aboard the Biscaglia during the incident, stated that an LRAD was aboard, but that he and the security attachment only had time to open the water cannons before gunfire and an RPG round forced them to abandon ship. No attempt was made to use the LRAD device during the incident.
In January 2011, the Spirit of Adventure, a cruise ship sailing through the Indian Ocean, deployed an LRAD system as part of its defensive measures when being pursued by pirates.
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. The Japanese fleet later escalated the use of LRAD, deploying it against a Sea Shepherd helicopter carrying a camera crew. Sea Shepherd noted that they had an LRAD of their own, but as of early 2010, had not put it into use 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.
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