when i was in my 40s i did an ear test with a sine wave tone generator and Sennheiser headphones.
one ear was good up to 17 kHz and the other one up to 17.5 kHz.

that's a long time ago and my hearing must have changed a lot in the meantime, but i can tell that as we age, we are not aware of those changes and i can't seem to remember any way it was sounding different then, compared to now.

See: http://www.blu-ray.com/community/gallery.php?member=Gelli
or: Axiom Gallery