The Long-Range Acoustic Device (LRAD) is a powerful loudspeaker that can also emit a sirenlike noise at a volume of up to 152 decibels. According to national regulatory agencies, even seconds-long exposure to sound greater than 140 decibels brings risk of permanent hearing loss. Some people, like the demonstrators who heard it used by police officers this year at the G-20 meeting in Pittsburgh, call the LRAD an acoustic weapon. A spokesman for its manufacturer, American Technology Corporation, calls it a "communication device." But all agree: It's loud.
Source: nytimes.comAdded: 12 February 2010