But it's not resolution, right? It's extra frequencies outside the audible range. Is there any natural process that would make those affect the audible components, if I were listening to the music live instead of a recording?
Only if the two are mixed in a nonlinear way (e.g. "heterodyned").
If a sonic and ultrasonic frequency are combined together, but a low pass filter doesn't pass the ultrasonic one, the ultrasonic one doesn't exist on the other end.
But it's not resolution, right? It's extra frequencies outside the audible range. Is there any natural process that would make those affect the audible components, if I were listening to the music live instead of a recording?