I have read many times about the Nyquist theory being half the sampling rate and that for a CD at 44.1kHz that the maximum frequency that can be re-constructed is 20 kHz which is above normal humans perceptive abilities. Fairly straightforward one would have assumed but i came across this paper below which shows a change in the brains electrical activity producing an emotional response to frequencies above this range.

http://www.av123.com/download/aps_auditory...onic_effect.pdf

James Boyk at Caltech has posted an interesting paper on the frequencies generated by musical instruments between 20kHz and 102 kHz! He also cites a paper that states that people react to sounds above 26 kHz even when they cannot consciously hear the sound.

http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

Your signature speaks extremely well to this concept:

("Not everything that can be counted counts, and not everything that counts can be measured" Albert Einstein).

I've posed this very same opinion at Club Polk after experiencing marked improvements in sound quality after upgrading speaker interface cables and interconnects.

I do believe that harmonics beyond the supposed human hearing threshold are in fact sensed and give timing clues that enhance soundstage height, width and depth, decay, tonality, ariness, and the overall the sound experience.