raise you hand if you can still hear 40Khz

[Fritz]

it is very rare that any human can hear above 16k let alone 20k or 40k. That's not to say that none can.

I used to work with a very accomplished and famous mixer what would have me "tweak" the playback head on the multitrack a 1/4db.
While he was an incredible mixer, that, to me, was show n tell.