I used to work at Sonos, long before their current app update debacle and headphone debut.

During the first aborted product effort to develop headphones, we were looking at a conceptual feature similar to this - selectively allowing people’s voices through the ANC chipset.

I don’t recall the exact approach the DSP folks were using (I was closer to the hardware for ANC) but they were really only able to figure out how to isolate the wearer’s voice by virtue of that signal having more power than all the others.

This is terribly cool. I wonder what other kinds of fun you could have with headphones. ANC chipsets are incredibly powerful and I’d wager their capabilities are not even close to fully tapped.