Doesn’t it have to do with the audio system though? I doubt that cheap headphones/speakers or even audio cards/stereos, etc. could produce a good signal. When I listen to the different files on my computer, I find that at some point (uh, frequency) it actually seems to get a little lower in pitch, and starts working it’s way back up. I’m sure that it’s because of my audio player and/or audio card and/or headphones. I can hear/feel something for all but the 22KHz, but they have distinctly different qualities/annoyance levels.