Honestly, I don't actually answer the question in the video. I give some reasons why some engineers say it's 60 kHz - but that's about it. What I do cover is Aliasing spurred on by a very interesting question about being the hear the difference between Sine Waves and Square Waves.

Sorry for all the "click-baity" title but there isn't a way to present this nerdy topic in a traditional way.

Here's the 7kHz demo I promised:
https://drive.google.com/file/d/1IoLJ...

Videos Mentioned:
D/A and A/D | Digital Show and Tell (Monty Montgomery @ xiph.org)
   • D/A and A/D | Digital Show and Tell (...  

Nyquist-Shannon; The Backbone of Digital Sound
   • Nyquist-Shannon; The Backbone of Digi...