This link might help.
Very old news. I've personally made recordings that make Boyk's plots look very tame.
They were made @ 24/96 and used extensively in some of the tests that I mentioned above.
What's left out of Boyks work, also, is the effects of air transmission.
Most of us don't put our ear into the violin or whatever, and most of us listen in a concert hall where the travel time of the reverberation gets up to on the order of a kilometer, too. (i.e. T60 of circa 3 seconds)
At 50% humidity at normal temperatures, your 20khz signal is going to be attenuated by about an extra 1.5 dB per 10 feet as compared to 100 Hz.
(that's extra attenuation, not 1/r^2 loss, of course)
Where's that get you in the back of the concert hall? What does it imply for reverb?
Let's talk 50kHz for kicks, now...
About .5 dB per FOOT. 10 feet, 5 db excess loss. 50 feet, down 25 db.
At 30khz it's about 3 db per 10 feet.
Physics is fun.
Air is a pretty lousy transmission medium, really, but it's what we have.
Is a handy reference.