xthread | The Emperor has no Ears...

Ganked from

dilletante, with some embroidery by me.

Humans can hear from around 20hz or so to around 22khz.
Well, some humans can.
We start losing the really high frequency bits when we're about twenty, and it's all downhill from there.

So, in the UK, they had the bright idea 'if we play loud tones that are high enough frequency that teenagers can hear them but adults can't, teens won't congregate.' This appears to work. Listen to an example here.

However, the Street finds it's own uses for technology, and the kids returned fire. They started passing around a high frequency tone as a ringtone, so that they could hear phones going off in class and the teachers couldn't. Hilarity ensues.

I was a bit skeptical when I heard this, so I asked a six year old I happened to have handy over to my desk, and requested 'please listen to this and tell me if you hear anything.'
She reported hearing both tones.

Yow. Just yow.

No cubs over fifteen, Billy!
Ever heard of a cub with a green flower?