Suppose that you all a panel of listeners all incapable of hearing beyond 20 kHz, they could still pass an ABX test with the following 2 signals: nothing and plenty of ultrasonic content.
There could be plenty of inter modulation distortion that is below 20 kHz, and that would be equipment related issues.
So in other words a panel of adult human beings! Yes, they could pass the test but you would not be testing for the ability to hear ultrasonic content, you would be testing for the ability to hear distortion within the hearing range of 20Hz to 20kHz!
Kiteki:- The Oohashi study has become infamous and a real pain in the audio world. When it became apparent that the Oohashi experiment produced non-repeatable results (a basic criteria for scientific evidence) it's methodology was examined and found to be severely lacking in several areas. Due to these facts and the large amount of evidence (repeatable) the Oohashi paper, it has been discredited. The Boyt paper you linked to did not provide any evidence of hearing beyond 20kHz. With regard to hearing Boyt just referenced the Oohashi paper, Boyt's paper was written before Oohashi's paper have been discredited.
To date there exists no reliable scientific evidence that humans can hear beyond 20kHz but a substantial body of scientific evidence exists which indicates that we can't.
I am looking for where his study has been repeated, and can't find one, well I'm not fully clear on if it's only Ooohashis study, but I'm talking about this one http://jn.physiology.org/content/83/6/3548.full#aff-1
I don't consider an ABX test "repeating" that study at all, and until I find a repeated study, then why should I believe it's been repeated? I agree with you a scientific truth should be repeatable but as far as I can see it hasn't been repeated, I repeat!! =p
I know the boyt paper doesn't provide evidence for hearing beyond 20kHz, it just shows that instruments resonate that high, that's all.
There is a substantial evidence that we can't hear beyond 21kHz, but the supporters of the hypersonic effect agree on this, and they claim that the tests do not show results through the normal air conducting pathways, but rather through something else, and even people with a hearing impairment showed a reaction to the hypersonic frequencies.