Just found a mad way of telling what voices are real or not.
Setup IP cameras facing outside the window, so i can tell when tv licence goons are at the buzzer - and one indoors in the bedroom, as a nanny cam for when baby arrives.
Side effect is - it has about a 3 second delay on it, before its played on my tablet. So if its an actual noise - it will play back. And if its in my head, obviously it wont.