How Much Are You Missing From 20khz to 45khz?

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X. Significance of the results
Given the existence of musical-instrument energy above 20 kilohertz, it is natural to ask whether the energy matters to human perception or music recording. The common view is that energy above 20 kHz does not matter, but AES preprint 3207 by Oohashi et al. claims that reproduced sound above 26 kHz "induces activation of alpha-EEG (electroencephalogram) rhythms that persist in the absence of high frequency stimulation, and can affect perception of sound quality." [4]
Oohashi and his colleagues recorded gamelan to a bandwidth of 60 kHz, and played back the recording to listeners through a speaker system with an extra tweeter for the range above 26 kHz. This tweeter was driven by its own amplifier, and the 26 kHz electronic crossover before the amplifier used steep filters. The experimenters found that the listeners' EEGs and their subjective ratings of the sound quality were affected by whether this "ultra-tweeter" was on or off, even though the listeners explicitly denied that the reproduced sound was affected by the ultra-tweeter, and also denied, when presented with the ultrasonics alone, that any sound at all was being played.

Don, thanks for the great reference.
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Oohashi's findings have never been confirmed by another
laboratory and the papers are open to criticism of their
procedures and findings.

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Kr4, do you think there's any value or advantage for a speaker to be able go above 20khz?
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Kr4
Do you hear any difference between a CD and SACD?

12-27-12: Mitch4t: Kr4, do you think there's any value or advantage for a speaker to be able go above 20khz?

I think that it is necessary that speaker response extend at least to 20kHz and have a smooth, well-behaved rolloff above.

12-27-12: Don_c55: Kr4
Do you hear any difference between a CD and SACD?

I do but I doubt that it has to do with FR. For example, at an audio show, I was able to pick out the addition of an ultra-tweeter that was effective only above 20kHz even though I have audiograms which show that my hearing at 20kHz is more than 20dB from reference.