pssst? hypersonic refers to much greater than the speed of sound (and is a nebulous term. supersonic is faster-than-sound, hypersonic is faster-than-supersonic, typically somewhere over mach 5). ULTRAsonic refers to high frequencies above the range of hearing.
the REAL problem with 44.1k sample rate is that at the nyquist limit (sample rate/2) there's ZERO phase information. high frequency sounds rely on phase relationship to maintain stereo directionality. in fact, a 22Khz sound thats at the wrong phase relative to the samples will be nulled out, and a 21.95Khz signal will pulsate as it goes in and out of phase with the sampling (this is similar to the moire effect of almost parallel lines). even at considerably lower and quite audible frequencies like 10Khz the amount of phase error introduced by sampling is significant and seriously messes with the stereo 'staging'.