HEY kiddies! I was bored and I found this off some forum....
go to:
http://www.sonypictures.com/mobile/messengers/index.html and when you listen to the files, tell me if you hear anything!
When I heard them, it was very clear, high pitched and "sharp" to my ears. Supposedly, quite a few adults can't hear it well or at all (well, according to the adults who posted on the forum, most of them said they couldn't hear anything or could make out some noise).