This is (one of the reasons) why you sign NDAs before discussing your technology.
We started SpeakerBlast in March 2013 & were meeting with Google in April 2013. We filed a provisional before the meeting & have a patent in the patent office.
https://www.youtube.com/watch?v=OJ9itwp_wYc&index=20&list=UU...
We revived it after seeing Google's April 2018 patent & are excited about finally getting it out to the public.