I played all of these on my HTPC on my home theatre system to eliminate equipment limitations. I consider myself an audiophile and I can distinguish the difference between Dolby Digital and DTS blindfolded on my equipment.
I am 27, I could hear all of them even with the sound of my Koolance Exos running, but it sounds like some of the higher ones are actually lower? The 17.7 KHz actually sounds deeper than the 16.7 KHz for example. Something doesn't seem right? The 14.1 KHz sounds the highest to me, ear piercing and almost inaudiable. The rest just sound like lower frequency tones at much lower volumes. I'm surprised at my age my hearing is still good with all the shooting I do, but then I value my ears and wear both foam plugs and a head set when I shoot.
My home stereo speakers have a range of 13 Hz to 30 KHz and I was able to hear everything except the last one at 22.4 KHz even though I could easily hear the 21.1 KHz, so I believe either my amp or my PCs SPDIF optical port is cutting it off. There was no perceptible audio playing even with the 30 KHz tweeter right next to my ear.
Actually no, while writing this, I just verified the file in an audio program and indeed the 22.4 KHz file is flat lined, there is no oscillation in the scope signal at all. Oscillation is present and easily discernable in all the other files.
As a FYI for people, your equipment could be a limit, and the .mp3 encoding process possibly clips out certain frequencies since its perception based after all, and the average human ear cannot hear them. In this case though it appears that the 22.4 KHz file is empty.
Update:
Reading previous posts, I can also conclude that it's probably Nyquist artifacts and aliasing causing some of the tones to sound lower than they should. I'm using onboard RealTek sound since my Audigy doesn't have a optical out port. Of course this mean my recievers' 24/192 DACs should be doing the work instead of a crappy PC sound card so the source of the problem is in the file, the software, or the SPDIF isn't true pass through and is modifying something.