Do we have any of these?
http://en.wikipedia.org/wiki/Long_range_acoustic_device
Futureweapons just had a segment on them... very interesting technology!
http://en.wikipedia.org/wiki/Long_range_acoustic_device
The long range acoustic device (LRAD) is a crowd-control and combatant-deterrent sonic weapon developed by American Technology Corporation.
The equipment weighs 45 pounds (20 kg) and can emit sound in a 15 to 30° beam (only at high frequency) from a device 33 inches (83 cm) in diameter. At maximum volume, it can emit a warning tone that is 150 dBSPL (1000 W/m²) at 1 metre, a level that is very capable of permanently damaging hearing, and 50 times the normal human threshold of pain (120 – 140 dB). The design range extends 300 to 500 metres. At 300 metres, the warning tone is 105 dB. The warning tone is a high-pitched shrill tone similar to that of a smoke detector, only somewhat louder.
Futureweapons just had a segment on them... very interesting technology!