Due to aging my hearing doesn't get better, I once have made an online test which said that I don't hear frequences above 16000 HZ anymore. I don't know if that's normal for my age (43) but it made me concerned.
That's very good - no reason to be concerned Did you know, that highest note of the piano has a frequency of 4186 Hz ?And that the interval between 16000 Hz and 20000 Hz is only major third?