The range of human hearing is higher than commonly reported, at least in terms of seeing a change in the brains of people hearing ultrasonics:http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm
"Recent work by Tsutomu Oohashi et al., published in June of 2000 in the Journal of Neurophysiology, shows that the brain may in fact be registering over-20 (or 22) kHz spectral energy. Titled "Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect", their paper discusses their finding that sounds containing High Frequency Components (HFCs) above the audible range significantly affect the brain activity of listeners."
There's a lot of information above 20 kHz.
Here's the original study:http://jn.physiology.org/cgi/reprint/83/6/3548
This is measured, and peer-reviewed. It turns out the 20 kHz limit was incorrectly arrived at in the first place! Think what that means. For one thing, it means that every CD ever made is cutting off frequencies too early, and that listeners who complain that CDs "don't sound right" and are "fatiguing" and feel like there's a "plate of glass" in the way could be making legitimate complaints even though they can't articulate exactly what the problem is.
All those claims about how all we need is 20 kHz and a brick-wall filter, all those "scientific" dismissals based on sampling theory, all of that was based on an original sin. They. Set. The. Cutoff. Too. Low.
It also means SACD is the only source available to end users that preserves ultrasonics. And it explains why SACDs sound better than CDs.
And it also means that receivers that cut off at 20 kHz are damaging the signal.