This wasn't here a week ago (just about). Very recent. It sounds as if a real life neighbor is mowing their lawn when my windows are closed. Sort of an even, low sound. Also sounds like a small propeller plane going by a good distance from my house. Hope either of those examples can give you a basic sense of what this sounds like. It's certainly not normal for the game. It is definitely in Wurm though, and is only present when Wurm is running (so not a speaker problem). Let me know if there is any info I can provide to help you track this down. Would also love to know if anyone else is having the same thing. Thanks! Rey.