Samsung TV's are known to do this kind of thing when they are within ear shot of people talking. If your phone has been set to allow access to its microphone f

Samsung TV's are known to do this kind of thing when they are within ear shot of people talking. If your phone has been set to allow access to its microphone for all the apps (or some other combination of unexpected apps), just as Android will activate the "location" permission from time to time on an update, then this kind of thing would not be surprising. Check your permissions.