Here's a really interesting post on the Sneeze http://www.thesneeze.com/mt-archives/000529.php about high frequency sounds that are used to deter youngsters makin' a ruckus in stores.
I'd post the mp3's here if I knew how...I could probably figure it out, but I'm lazy and I should actually be asleep right now.
Anyways, I could hear a high pitched oscillating sound on #1 only if I put my ear up to the speaker. For #2, I suggest you stand back. It made me queasy and had me shaking my head for five minutes trying to get rid of the sound.