DrowseyMonkey, has this on her blog, and thought I'd try it myself. I failed! I was skeptical at first (if I really can't hear it, it must be a hoax), but then I had my six year old listen.
"I can hear it!" she said.
(thanks, kid ;) arrgh.
I asked her to describe it and she couldn't. I then had her close her eyes, and tell me when the sound started, and when it stopped (to make sure she really could hear it, and wasn't just playing along). Sure enough, she told me when it started, and as my eyes followed the audio player status bar, when it stopped. Lo and behold, it appears to be legit.
Give it a try yourself, and may you have a better result than I did!
Created by Train Horns