I am in my 40s and I can still hear up to 18000 maybe 18500kHz (can't hear 19kHz) but that I am sure will go away soon.<br>That being said, I can only hear it if my gear can reproduce it i.e. i can hear the 15kHz hiss on your video way better with my AKG K712 with my portable DAC connected to my PC than with my smartphone using the free headphones supplied with it (connected directly). But I guess that has to do with the Dac, the Amp as well as the shape of the frequency response of the headphones.