I recently found out about a product called the Mosquito security system. It uses high-frequency sounds to repell teenagers away from an area. Adults can't hear the sound due to age-related hearing loss. This is a real device, I am not making it up.
Some teems are using it to their advantage, however. As the article says, these tech-savy kids are using the sound as a ringtone on their cellphones so they can use their phone in class without the teachers knowing. Genius!
So find out for yourself. Can you hear the sound? Apparently, you start losing your ability to hear this frequency around age 20 and by 30, the vast majority of people can't hear it at all anymore. But kids sure can. If you don't believe me, find a child or teenager and play it for them. They'll hear it. :-)
Read more at Google News.