Valve's Headphone setting vs Dolby Headphone and CMSS-3D

Valve's headphone setting doesn't change the sound depending on if it is in front or behind you. The sounds in front and behind you sound different in real life because our ears aren't symmetrical. Both CMSS and Dolby do this but Dolby is more customizable and sounded better in the end result.

However, neither of them appear to be able distinguish between above and below in the few games I've played.

I suspect the barbershop recording had the microphone placed in an actual ear or ear substitute to simulate it.

Google "head-related transfer function" if you want to know more.