[jsjohnst]

> Truly exceptional (never documented) human ears might technically be capable of faintly hearing 23 or 24kHz tones, but that ability is likely to manifest and deteriorate over the course of (at most) a handful of contiguous years in their life and never return.

When I was in my twenties, I could easily identify sounds in the 23-26k range (tested using professional gear more than once). When I was younger it was quite painful to hear as my ears were so sensitive to it (as a young teen, I would wince in pain when a monitor was left on without an input signal even in a room of people yelling noisily at each other). Even now in my late 30s I can still readily hear in the low 20k hz easily.