I am 70. My upper limit is now 9000Hz. My hifi stereo system still sounds the same. I guess my brain is filling in the missing frequencies.,(reply>), Well then you probably didn’t hear the high pitch in the end. It was morse code that said “Never gonna give you up”. At least you’re immuned to high pitched rickrolls, so I guess that’s your silver lining?,(reply>), geocarey   That is absolutely true.  Your mind compensates for shortcomings in all your senses.  It does this in a way you cannot discern.,(reply>), If you can't hear the morse code at the end card, put a portable AM radio tuned to around 530 KHz up to your computer's speakers. You can clearly hear it thru the AM radio. Turn up your computer's volume to max.,(reply>), As you age, your brain starts to make symbolic shortcuts. You think you see or hear something,  but more and more of it is memories.,(reply>), Most likely you just lost your hearing so slowly that you forgot what those frequencies sound like. My freinds grandpa has a really good home theater and hifi system in his basement that we use whenever we hang out there, and its kinda disappointing because the calibration and speaker placement is really messed up because his grandpa can't hear well enough to realize that it sounds like garbage due to the way its set up. Its all pretty decent equipment, its just setup wrong.<br><br>One time we played an old cassette in it, and I could hear the azimuth was completly off. I fixed it, and his grandpa couldn't hear the difference, while my friend was shocked that cassettes can actually sound really good with nothing but a quickly done by ear calibration.