How Good Are Your Ears? How Good Are Your Headphones?

I found this link on an interesting thread over on the audiokarma.org discussion board.  It lets you test your headphones.  As an aside, it also helps test your ears.  You might be surprised to find that you can't hear some of the higher frequencies.  Your high frequency hearing deteriorates over time.

http://www.audiocheck.net/soundtests_headphones.php

The obvious next question:  Why pay for what you can't hear?