Pezzab
New Head-Fier
I'd imagine even if you were able to hear these frequencies they'd easily get swamped in a mix.Hardly anyone hears 18 kHz! Many people don't hear anything at 14 or 15 kHz!
In music, nothing happens at these high frequencies either. 20Khz is theoretically audible - but unrealistic. 48kHz are interesting for bats.
I used to be able to hear bats but only if there was no background noise.