In any event ultrasounds can be audible under the right conditions. If cables change the ultrasound components of a music signal then they will change the sound of a speaker. Whether someone can hear the difference is a different question.
I'm inclined to suggest this is an error in semantics. In this case, ultrasonics are not audible (hence why it is called ultrasonic), but rather the audible distortion products of two ultrasonic sources.
As I recall, it is the non-linearities of air that this process exploits when mixing two ultrasonic signals. When mixed, they produce intermodulation distortion, with the primary objective being the lower sideband. They should produce another image even higher than the sources, but then, we couldn't hear that either. Of course, this is the first-order distortion pair, there will be a bunch more second-, third-, and so on, orders at much smaller amplitudes - some of which would fall in the audible range.
The technology is quite interesting, and has many uses, but critical listening of music is not one of them, in my opinion. Listening to 100% distortion is not my idea of a good time. Plus, I'm not sure I'd be able to tell the difference between various audio cables and power cables using this distortion laden technology (just to try and keep this on topic).
As I recall, the question that sparked your interest in this ultrasonic diversion was can we measure things we can't hear (sorta paraphrased)? I'm not the original asker, but I'm guessing it wasn't about things outside the frequency range of hearing, but rather phenomena within the range of hearing. We measure things beyond human hearing all the time. If we couldn't, we wouldn't have: radar, radio, microwave ovens, computers, cell phone, etc. On the other end of the spectrum (infrasonic), we wouldn't be able to measure earthquakes and other low frequency phenomena either.
Using my way-back machine, I seem to recall this thread is about why can't we discuss cables without being attacked, or some such. That, plus the subjects Negotiableterms outlined are the acceptable topics in our effort to reach the goal of a thousand and one posts.
Note: I did not read your link, but I did read up on it a bit many years ago. If I've confused what I learned then with what you're talking about now - so be it. No wait, I meant, my apologies.
