I remember when I was visiting my brother in Las Vegas and somewhere not too far from his house there was a police raid or something going on. There were quite a few helicopters hovering above the scene. Amazingly, my brother could tell me which models of helicopters they were (and I guess even the engines, but there was no way I could confirm that), before we could even see them. I was impressed! Of course this only impresses people if they can at least visually recognize an aircraft type to begin with.

As a rookie, I can tell an airplane from a helicopter and a turbine from a piston engine by the sound of it. Which is enough to impress the ladies. Well, most ladies, not my wife who calls me a smartass when I do that. :-)