I do not remember where I first heard about the “ringtone that adults can’t hear” but I figured I’d look it up, as my hearing is pretty poor (what?) and I wanted to test this whole thing out.
Luckily it didn’t take much to find someone with a recipe, in this case, it was JimXugle’s comment on Digg which goes like this:
Generate > Tone
So I fired up Audacity and started to experiment.
I started with 18000 Hertz, and I could not hear anything. I then started at the low-end instead, and I could hear 12000 Hertz, and 13000 Hertz, but 14000 Hertz? No good…