[isostatic]

Tested my kids - they could hear an alleged 21khz tone out of laptop speakers. The actual level of the tone doesn't matter - it was above my level of hearing. Wasn't a double blind, but they told me when it started and stopped based on a bash script with random intervals.

[BenjiWiebe]

I'm 20 but I can still hear 20 khz, albeit not very well.

[isostatic]

I could when I was 20, did a proper hearing test when I joined my company. 15.625khz was very noticeable - I scoffed at the old timers who couldn't hear it.

I can no longer hear it. Still I can hear 1khz, so that's what's important.