Comment by cmer

That article describes hetrodyning which happens because ultrasonic frequencies at high amplitudes interacts nonlinearly with air. You are not going to see that effect with sound waves generated near the audible spectrum, and normal loudspeakers are going to generate ultrasonic sound waves.

Recording music is supposed to be a snapshot (with room for interpretation) of the composition at play.

Trying to record an edge case like this is the same as recording in a room with bad acoustics. So you end up with some weird (but not faithful) representation of the sound which is a snapshot of the microphone's characteristics and directionality of the ultrasonic tones. It's not reasonable to assume any microphone will behave exactly like a human ear. Even if you could, you're going to have to mimic the tiny random movements a normal person would make listening to a sound, movements which would definitely impact the perception of the sound, because microphones are much more stationary than any human would be.

The "different sounding" argument two posts above is silly, because sound is almost never that monochromatic, and if it is, it's usually boring. Also I don't understand how missing out on an odd order harmonic would be a bad thing :) The reality is none of these arguments are based in a reality of what people would hear, and because of that, the arguments aren't practical.

In reality, 20 bits at 48kHz (or 64kHz) would be more than acceptable for even the most discerning of ears and probably the most practical in terms of space and fidelity, but it'd be a weird format to distribute in.

That's very cool, but it requires pretty high-intensity ultrasound to be noticeable. I doubt that will be the case with ordinary music.

> Basically, if you produce two ultrasonic frequencies, they will create an interference pattern at a much lower frequency than either of the individual frequencies.

So the interference pattern will be made up of one low frequency sound and higher frequency harmonics. Once again the higher frequency harmonics are redundant, because you only need to record the lower frequency sound.

The only possible way ultrasound can be picked up by the ear is if the ear has a non-linear response to the input sound. Going by the information in the article linked, it is highly unlikely that any significant non-linearity exists in the ear.

Me and my brother would sing at each other in certain tones such that we created harmonics in both our ears. It wasn't pleasant, but it was interesting. Regardless, I'd smash my equipment if it made harmonics like that.

If that is true, surely in your up thread example of recording a triangle, the "impact on lower then 20kHz frequencies" would already have happened during the recording process in between the triangle and the microphone, and would have been captured perfectly on recording equipment that's proven capable of capturing everything below 20kHz? So we'd "hear" the effect as part of the recording instead of requiring it to happen in our listening room…

>That's been proven a million times.

Then you should be able to provide at least one citation.

If you're not going to hear the frequency, then there's no reason to record it, so I don't see what you're objection is.

In other words, your theory is that the superposition principle doesn't hold for sound waves.

Note the lack of citation

"A/B or GTFO," I believe is the parlance of our times.

Yes. A 40KHz tone and a 41KHz tone will interfere with each other and can create 1KHz tones that are audible. Edited to correct error, thanks anechoic.