About two years ago I had my hearing checked. Just starting my forties and my high frequency hearing was pretty good considering the crap I've been sticking in it during my younger days. My left ear rolled of at 18.5k and my right ear at around 18k. Not 20 to 20 but I was fine with that. I could still hear 20k if I cheated and turned the volume up a little.
Ever since owning the LCD2 and HE6 I noticed that I was enjoying music a little too much and many times at quite high volumes. I bought a SPL meter and tried to keep the volume in check at around 87 to 90 db. Flash forward a year and a half to today. I just checked my hearing again with some test tones and both my ears start to roll of at 16k! Ahhg!! I'm a old geezer now. Like the geezers I secretly pity because they can't hear as well as I can.
Flagship ortho owners please use me as a example. Protect your hearing. Be especially careful of that damn HE6 and speaker amps and countless hours of jamming late into the night.