Acoustic "beat tones" aren't "real" tones— you hear them because of non-linearies in the ear-brain system, but you have to hear the initial tones first. (Well, unless you're talking >>130dB SPL levels where the air starts becoming non-linear, but then lower frequency recording would capture it fine)
If you could hear subharmonic beats from ultrasonics then it would be _very_ easy to demonstrate, alas.
so without very high power sounds and the nonlinearity business the whole "Sound from Ultrasound" wouldn't work? Huh, I guess all this time I misunderstood it.
Well, what I can think of is that of course you need to sample at > 2*max frequency if you do uniform sampling to avoid aliasing (by Nyquist), but that's not the same as playback.
Yes, there will be inter-modulations from higher frequencies. There are also from the audible spectrum but if the amp is linear enough they will be low.
nullc|14 years ago
If you could hear subharmonic beats from ultrasonics then it would be _very_ easy to demonstrate, alas.
zachrose|14 years ago
cop359|14 years ago
for those curious http://en.wikipedia.org/wiki/Sound_from_ultrasound
marcusf|14 years ago
crististm|14 years ago