The LRAD, or Long Range Acoustic Device, is an acoustic-based non-lethal crowd control or hailing system that is produced by the LRAD corporation. The device is designed to help deter or warn people at a much greater distance than traditional audio speakers. LRAD units range in weight from 15 to 320 pounds, and emit sound at 2.5 kHz reaching levels of 137 dB at close range. The system is used by the United States military, commercial security companies, and law enforcement to transmit warnings, encourage changes in behavior, or to deter aggressive behavior. The system has also found use to deter wildlife from airports, wind farms, and other sensitive industrial activities.
How Does the LRAD Device Work?
The LRAD emits sound in a directive manner at a beam angle of approximately 30 degrees and 2.5 kHz. It makes use of an array of specifically designed drivers that are connected in parallel. Then, small point-source acoustic devices make use of the known inverse square law to help create the focused beam of acoustic emissions. Based on the design of the device, human beings within 330 feet or 100 meters of a directed LRAD transmission at full power will find it extremely painful, with the device being powerful enough to cause permanent hearing damage if a person is exposed to transmissions for too long of a time period.
What are the Uses for the LRAD?
The LRAD was initially developed to provide the United States Navy with a non-lethal deterrent for unknown shipping following the attack on the USS Cole in October of 2000. It was designed to provide additional time for sailors to determine the intentions of unknown shipping and to aid in the decision to use deadly force or not. Since the device has an effective range of 3,000 meters, it was widely adopted. Since that time, the LRAD system has been used by the U.S. Army and other DoD agencies ashore to transmit warning messages in the native language as well as to dissuade behavior for personnel at close range who ignore warnings. In the civilian sector, the LRAD has been used by police to break up riots, to deter pirate attacks, and by the Japanese whaling fleet to deter activists. Research continues by the LRAD company to refine the units design, increase range, and options for use in the field by both civilian and defense units.