Non-lethal sonic warfare
In November of last year, the cruise liner Seabourne Spirit was attacked by pirates off the East African coast. After being hit by a rocket-propelled grenade, the crew defended the liner with a sonic weapon, a Long Range Acoustic Device (LRAD - not to be confused with the Lilac Rainbow Allience of the Deaf). The device has a diameter of 84cm (33in) and a weight of only 24kg (53lb), consisting of a dish that can generate a frequency of between 2100 and 3100htz at 150dbls, and focus the sound wave into a beam 15°-30°, effective for up to 300 metres (985ft). In addition to potentially damaging hearing, the intensity of the sound at such frequencies physically compels the target to get away. The LRAD was devised to protect American Navy vessels following the terrorist bombing of the USS Cole in 2000. Since then, it has been used in regions of Baghdad, Fallujah, and other parts of Iraq. It was also used against civilians in New York City, during the protests of the 2004 Republican National Convention.
But non-leathal sonic warfare does not stop there. In parts of Britain, some shops have Mosquitos. Developed by Compound Security Service, the Moscquito is a pretty simple device that produces a continuous high frequency tone. The frequency, however, is inaudible to most adults, who have already suffered some hearing loss by age 20. So, its primary use is to keep young people away, loiterers and troublemakers. The device also has a Pavlovian conditioning effect, in that people unwittingly exposed to the sound in a certain place will avoid going there again, possibly without knowing why. I wonder if it works on dogs too.
Louder, louder, louder! ForteanTimes.com
A friend of mine told me recently, that school kids in Britain figured out that they can put high frequency tones on their cel phones, which would be inaudible to their teachers. However, the instructors can often figure out what’s going on, when half the class starts wincing or covering their ears.
Comment by alexei — May 2, 2007 @ 9:33 pm