<span class="SFPTagline"> From SCIFIPEDIA </span>

The long range acoustic device (LRAD) is a crowd-control and combatant-deterrent sonic weapon developed by American Technology Corp. of San Diego, California.

The device was intended to be used by American warships to warn incoming vessels approaching without permission, but it has come into use more generally as part of America's nonlethal force arsenal.

The cruise ship Seabourn Spirit employed an LRAD to repel pirates who attacked the vessel with RPGs off the coast of Somalia in early November 2005. 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 device was also used by police in New York City during protests of the 2004 Republican National Convention.

The LRAD device is 33 inches in diameter, weighs 45 pounds, and can emit sound in a 15 to 30° beam (only at high frequency). At maximum volume, it can emit a warning tone that is 150 dBSPL at one yard's distance, a level capable of permanently damaging hearing, and 50 times the normal human threshold of pain (120–140 decibels). The device's useful range extends from 300 to 500 yards. At 300 yards, the warning tone is 105 dB, and is a high-pitched, shrill tone similar to that produced by a smoke detector, only louder.

Carl Gruenler, former vice-president of Military and Government Operations for American Technology Corp., says that being within 100 yards of the device is extremely painful, and its use should be limited to 300 yards to be effective.

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.

Other nonlethal weapons are being developed by the military, such as the Active Denial System, which uses a painful energy beam to discourage would-be attackers.