@cwebber @simon @profdiggity FWIW, the kind of voice recognition you'd need for this kind of ad targeting has been feasible with 2017-phone-level computing power since the turn of the century. (he says, as he turns to dust and blows away) Honestly with 2017 level phones you could probably run a continuous voice recognition transcriber and not use a noticeable amount of CPU/power for it.
The transcriptions would be kinda crap in many cases, but for ad targeting that'd be just fine.