Haven't tried it with a coat-hanger, but in the 50s I read about the same idea with a fork (the eating kind, not the digging kind!)You can ring the changes (pun intended) with a couple of forks, a fork and a spoon, different sizes, and so on. You get a really good deep tone, and it's alnost inaudible to everyone else; of course, this menas they'll think you 're barmy, but you get used to that.

Then there;'s the famous lions's roar: make up one half of a string-and-in-can telephone, then rub something like violin rosin or candle wax on the string; when you pll the string ently, lttting it slip throuh your fingers, you get a kind of growling noise. You can vary this from the eponymous lion's roar to a creepy old dungeon door-creak.

Steve