I'm curious that the digital protocol in use works past 22KHz. As far as I know Mpeg does not neither does SPDIF, and I'm not that sure about the sound card. Somewhere in the chain is a digital to analog converter, it has a clock, signals higher than 1/2 the clock frequency are not possible.

At 59 I can hear to about 14K at low levels, higher frequencies at louder levels.

My wife could easily hear bats and ultrasonic burglar alarms (I think they run 30KHz) In fact there were stores she couldn't enter because of the loud irritating whistle from these alarms.

CRT TV sets (not HDTV) run the horizontal scan at 15,734 Hz most young people can hear them fine.