New loitering prevention technology?

[sarahkate]

trainhorns.net/sound/

Apparently, this is some new technology to reduce loitering? Even though it says people generally 25 and under are only able to heart his noise, my dad can hear it. Trust me, the 3rd time I listened to it, I could hear it more than the other 2 times before and wanted to die.

Play it for your parents, and see if they hear it!!

[dominic]

There was a post made on listverse.com concerning "Top 10 Incredible Sound Illusions" and this phenomena was explored.


"This is a sound that can only be heard by people under 20 (some over 20 can hear it but not many) - it is a sine wave at 18,000 Hz (by comparison, a dog whistle sounds at 16,000 - 22,000 HZ - meaning your dog can hear this “under 20s” sound as well). This sound is used by some teenagers as a ring tone on their mobile phone so that only they (and others of their age group) can tell when the phone is ringing. It is also occasionally used in England to play very loud in areas that authorities don’t want teens to congregate in, as the noise annoys them. As people get older they lose the ability to hear higher pitched sounds - that is the reason that only young people can hear this sound - it is too high for most people over the age of 20."

Down the list.
listverse.com/miscellaneous/top-10-incredible-sound-illusions/