thecages

Here's a cool little subversion courtesy of Digg.
Some years ago the first devices were introduced into malls etc. to drive away loitering teenagers. One of these emits a high-pitched whine which is more audible to (undesirable)teens than what it is to (desirable)older folks.

Score one for the old fogeys. Not quite - a British teen has come up with a ringtone which uses the same frequency range which will supposedly provide stealth rings in a classroom etc.

It seems that as we get older we lose the top-end of our hearing range and the ringtone takes advantage of this to let kids go under the radar (at least to some extent) of their snooping parents.


The downside is that the tone is horrifically irritating.


Last year I played around with a cool tone generator from NCH and had a lot of fun at the bottom end of my hearing range.
My favourite tone is here.
It uses two low-end frequencies per channel(stereo) and is vaguely binaural.

What makes it cool is that (when played on a good quality hi-fi that will produce the tone correctly) the dynamics changes substantially if you move around it.
This is best done setting up the speakers a few meters apart in the middle of a room and walking around it.
Various aspects of the tone slide in and out of hearing range in different areas.
There's no need to turn it up too loudly since the effect is actually more interesting at relatively low volumes.



Read some interesting articles a while ago on research undertaken to study the sub-audible characteristics of Cathedral organs and choirs - must look into that again...