Right around 18.5khz there's a sharp falloff on pure tones no matter how much I pump the volume. I use a loudness meter that shows me the freq spectrum to confirm that my speakers and headphones are producing a pure constant tone.
On the tests at: "https://www.audiocheck.net/blindtests_frequency.php?frq=14" I can get 10/10 on the 10khz and 11khz test, 9/10 on the 12khz test and then it's just guessing at 13khz and higher.
High hats tend to fall around 16khz and I have been able to differentiate on audio tests just by listening to high hats but that has more to do with how aggressive the codec is and not necessarily my hearing capability. I enjoy piano music and using the Apple afconvert tool I've been able to get piano tracks down to under 100kbps and they sound fine to me which is pretty amazing.
I cannot use some of the more popular Berydynamic headphones because they sound too trebly and some pop songs are physically painful for me to listen to (eg the marimbas at the start of Ed Sheeran's Shape of You are like ear daggers on the 880 headphone and unlistenable on the 990's). I wonder if some of that brand's popularity comes from older ladies/gentlement being able to hear treble in the music that they otherwise wouldn't hear at all.
One thing is I suffer from tinnitus or something because at night I am always aware of a constant noise or "roar" in my hearing as well as my visual noise in my eyesight. I have pretty terrible eyesight so my hearing circuitry may have just amped the volume a bit to compensate (like upping iso on a camera).
In both our cases I wonder how much of this is just our brains have learned to pick things out of the signals are ears give vs our ears actually being more/less capable than other people. I think my brain has just had a lot of practice. I've always loved music, practiced classical piano hours a day when I was younger, and cut my teeth programming learning DSP algos for audio processing. I recently did a hobby project involving reproducing NES music from ROMs and that involved just listening to raw square/triangle waves and literally just following intuition to get everything to sound right. I'm willing to bet my case is one more of training than raw ability.
Part of that is also your brain. Master sommeliers can tell you which vineyard the grapes in a wine came from, sometimes even which side of the vineyard. Yet give those sommeliers a white wine with red coloring mixed in, and they won't immediately notice.
I've actually met one other person that said what you say, if they really try they can hear a minute difference with cymbals and hi-hats in regards to lossless vs high bitrate lossy, but they also said they had to strainingly focus on the listening and they would never listen nor enjoy music that way.
> In both our cases I wonder how much of this is just our brains have learned to pick things out of the signals are ears give vs our ears actually being more/less capable than other people
A little bit of both, I think. Your ears are naturally more sensitive, so you put the volume on your speakers a lot lower, which teaches your brain to pick up low volume stuff better. I'm always worried the downstairs appartement can hear my 'loud' TV at night, but they've told me they can't hear a thing.