What no one has pointed out is that a good quality phone should not pick up the background noise to analyse!
With iPhone's popularity everybody is conditioned to know such a thing does not exist
Remember that Google is writing a mobile OS... Big thing there.
For background noise removal, all that happens AFTER the mic. So it's pretty much trivial to get the full mic, find the background noise and analyse it, then process the sound to remove the background noise for the normal phone call.
Oh, and did you know that the same thing is going on in other consumer electronics?
(Yeah... the rabbit hole goes down pretty deep...)