According to several news sources (including USA Today), the sonic weapon used by the Seabourn Spirit to deter the Somali pirates who attacked the cruise ship in the Indian Ocean on Saturday was a long-range acoustic device (LRAD) originally developed for the U.S. Navy by American Technology Corporation of San Diego. The non-lethal weapon was designed to deter attacks on ships like the bombing of the USS Cole in 2000, an attack that was carried out in a Yemeni port by suicide bombers who approached the Cole in a small boat packed with explosives.
LRAD permits broadcasting of messages or sounds (including ear-splitting noises) over long distances. Its use can cause permanent hearing loss at distances of up to 100 yards.
At present, the device is deployed on U.S. Navy ships operating in the Persian Gulf and as part of the force protection kits of the 1st Marine Expeditionary Force in Iraq. A number of cruise ships also carry the LRAD, which, because the sound it generates is focused in a particular direction, can be used without harming its operators or others not directly in the path of the sonic pulse.