Sonic device deployed in London during Olympics

The American-made Long Range Acoustic Device (LRAD) can be used to send verbal warnings over a long distance or emit a beam of pain-inducing tones. The equipment was spotted fixed to a landing craft on the Thames at Westminster this week. ... broadcasts focused, highly intelligible, multi-language messages, instructions and warnings over distances up to 3,000 metres to peacefully resolve uncertain situations".... capable of producing deafening sound levels of 150 decibels at one metre....