Crowd Control: the LRAD was designed in the US, tested in Iraq and now it's coming to the London Olympics to keep protesters/terrorists (same thing really) away.
American-built 'long-range acoustic device', used by US military in Iraq, can produce deafening 150db levels at one metre

The Ministry of Defence has confirmed that a device that can be used as a "sonic weapon" will be deployed in London during the Olympics.

The American-built long-range acoustic device (LRAD), which has been used by the US army to control crowds in Iraq, can emit an ear-piercing beam of sound.

An MoD spokesman said the device, which can also be used as a loudspeaker, was among a "broad range of assets" being used by the armed forces to provide security during the Games.

He said it would be used primarily in loud hailer mode to issue verbal warnings to any boats on the river Thames that were causing concern.

But some versions of the device, which was used this week during Exercise Olympic Guardian, are capable of producing deafening sound levels of 150 decibels at one metre.

"As part of the military contribution to the police-led security effort to ensure a safe and secure games, a broad range of assets and equipment is being used by our armed forces," the MoD spokesman added.

"This includes the LRAD which will be deployed during the Olympic Games primarily to be used in the loud hailer mode as part of the measures to achieve a maritime stop on the Thames."