Can You Hear Me Now?

This just in from the BBC:

The 'Mosquito' sonic deterrent device was installed by the Wyvern Theatre in an attempt to stop groups of up to 100 youngsters from gathering around Theatre Square.

It was named the 'Mosquito' because the sound resembles that of a buzzing insect. And it works by emitting a harmless ultra sonic tone that generally can only be heard by people aged 25 and under. In trials, it has proven that the longer someone is exposed to the sound, the more annoying it becomes.

Crime Reduction Officer Bob Walton elaborated further: "Effectively, it's a transmitter which sends out a specialised frequency noise which according to the manufacture is particularly audible to young people under the age of 25.

He said: "I'm in my fifties and when it's turned on all I can hear is a very faint buzz. But I understand from young people who have been exposed to the noise, it is very annoying."

Swindon's anti-social behaviour co-ordinator Cheri Wright says it is working well.

She said: "We had a meeting with local retailers arounds here - after it had been installed for around three weeks - and feedback was really positive.

"Everyone was saying there has been a marked reduction in criminal damage and problems with the shops, so they've really welcomed it."

I first read about this story at TheSneeze. But what was really amazing was some of the testing that Ochen K. did.

Check this out...

Here is the sound they are using... CLICK ME. Sounds to me like ordinary street background noise.

Accouring to Ochen K., there is actually a sound there about 15,000 Hz. He used his spectral analyzer to find it. Here is what the same sound sounds like when the "Mosquito" noise is slowed down a little... CLICK ME.

It seems that most humans are born with the ability to hear frequencies from about 20 Hz (low) up to 20,000 Hz (high) but that range shrinks as we get older. The guy in England created the device to target young people who could hear that higher frequency. AMAZING!

Check out your threshold at Ochen K's site. It will blow your mind.