http://www.teenbuzz.org/ I can barely pick up 19kHz and I'm 42 years old. However, I am turning the volume up.
If all you hear is the hiss like air escaping a balloon then your speakers are up too loud... I dropped out at the 45 year old range, a full 10 years early. (too many concerts).
I can hear all of them. I attend on average a concert a week, but for some reason my hearing is still very good. On the other hand, my vision is crap without contacts.