You guys must all have blown your eardrums. I can easily hear well over 20kHz . For example, I created a [.wav file] that plays a sweep from 11kHz all the way up to 44kHz and I can easily hear it the whole time.
Okay, now where is the trollface emoticon?
okay,, obviously I am being facetious. If you haven't yet figured out what I did, then you should check out the wiki article on aliasing and Nyquist frequency. Because the sample rate of the wav file is 44100 Hz, the nyquist frequency is 22050Hz, which means the part of the signal above 22050Hz is aliased to a sound less than 22050Hz; hence it is audible with this sampling rate. Okay, stop flaming me now, thanks!
I'm afraid I may have concealed the hidden message in my post a little too well. As with anything, always read the fine print.