I work in Ad tech. No one is capturing anyone's voices to serve them ads via their mobile devices. People are often segmented by location and proximity to interests, however. If someone nearby (a neighbor, perhaps) searched for pest control? Guess what, you're now in a likely segment of people looking for pest control. Boss searched for a canon printer at work? You're in that segment, too, until your interest score drops and you're removed from that audience segment. This is pretty universal - you can even see what Google's got you pegged for being interested in by going here: https://www.google.com/settings/ads
TL;DR: There are like-minded people in very close proximity to you, searching for the same things that you search for/mention/use/lust after, and you're getting lumped in with them.