In message , Emil Tiades
writes
On Sat, 16 Feb 2008 23:34:24 GMT, geoff wrote:



All you need is a tweeter and a 20KHz oscillator!

From the "this is what you old farts would hear" articles, it's more
like beats - so you would need two oscillators, somewhat higher than 20k
of course

You would also need a teenager in a cage for tests

Prolly quite simple to trap a couple



--
geoff