My wife has proven to be really good at guessing movies by sound alone. I started tracking without her knowledge initially and we're half way through our movies and she's gotten 79.16% right within the first 10 seconds*.
To sleep we play a movie, audio only. If we wake up we'll restart the movie. It has to be a movie we like enough for it to be on but not so much we won't sleep. So it not every movie we own, just 106 movies on the list.
It takes is about 4 months to get through it and I decided this time I'd keep score without telling her as I'm always the one to put a movie on. A few weeks in she said I should start keeping score, I laughed and told her I already was.
I guess after 25+ years being either we know each other pretty well.
*The 10 seconds excludes intro sounds that aren't unique. Like the Disney sound.