I present the following recent experiences:
Exhibit 1: I was watching a story on CNN about a ringtone that only young people are able to hear. I think it was called Mosquitotone, or something like that. It is a high-frequency tone that takes advantage of the fact that high-frequency hearing is the first to go when people age. So kids can text message their friends in class without the teacher knowing about it (I'm going to refrain from commenting on this). They played the tone at the end of the story, and I had no problem hearing it, despite the fact that I have significant hearing loss in both ears. BTW, it is a highly annoying sound.
Exhibit 2: I messed up my back today. Granted, I did it while trying to wrangle a mass spectrometer into place (something I don't recommend).
So my ears are young and my back is old. Great.