What does not go away and allows 70 year olds to evaluate tweeters..is... temporal acuity.Teo_Audio: Your post re "temporal acuity" is quite interesting and telling.
Our hearing is based not on frequency range but on complex temporal harmonic transient (macro and micro) timing position, level, and interleaving. Frequency extension is only part of the story………..
One can measure but one has to measure and compare what is important. So far, electronic measurement and human hearing as a coupled system of relation (to attempt scientific discernment for the purpose of application of engineering), is almost missing the whole boat.
Because of my lack of knowledge in this area, I'm unable to add to or counter your discussion.
However, it does speak to my personal experience and conclusion that measurements have little, if any correlation to the end result of equipment selection and listening enjoyment; whose underpinnings I've found to be less frequency response related and more related to the you-are-there (holodeck) experience.
I enjoy music reproduction in any and all of its forms. But the illusion of being in or at the performance is what the equipment in my audio room provides. It is so much more than just an accurate frequency response.
Over the decades, I've wanted and wished for an objective (read measurable), easy and perhaps less expensive method of equipment selection; but my listening experiences have resulted in my concluding otherwise.