There's an interesting story in the Guardian. It's a news piece about the annual invasion of several lovely beaches in Cornwall by unruly teenagers who hang out there all night, get steaming drunk and make loads of noise and mess. It's become a real problem for locals in places like Polzeath and Rock, potentially damaging the tourist trade too. In 2006 dispersal orders were issued to 274 people banning them from Polzeath for 24-hour periods. Shopkeepers and bar owners confiscated more than 400 fake identity cards from underage drinkers.
The solution? Apparently it's an ultrasonic device that emits a high pitched tone called the Mosquito which takes about eight to 10 seconds to be heard by the human ear, so if people are walking past it will not bother them, but if people hang around it will. That all makes sense... but get this: according to the Guardian. "The devices... emit an annoying high-pitched sound that can only be heard by young people."
Seriously? Does the human ear differ that much between the old and the young? It must be a wind up. I'd have thought it's the younger kids who blast their eardrums with their iPods all day long who are least likely to have damaged hearing so won't hear this noise...
Well... apparently not. It seems that there is a very real medical phenomenon known as presbycusis or age related hearing loss which, according to The Merck Manual of Diagnosis and Therapy, "begins after the age of 20 but is usually significant only in persons over 65". It first affects the highest frequencies (18 to 20 kHz) notably in those who have reached 20 years of age". Apparently it is possible to generate a high frequency sound that is audible only to teenagers. Awesome... let's install it on the top deck of every bus right now!
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