Bullroar

If your a "child of the 80s" like me you probably remember the movie Crocidile Dundee, and it's Sequel. In the second movie Mic Dundee goes up on the side of a mountain and makes a "telephone call" to all the locals. He uses a Bullroar which is something the aborigines have been using for hundreds of years. It produces a thrumming noise kinda like the prop of a cessna airplane.
I tried carving one of these a long time ago and while it did sort of work it wasn't as nice as I had hoped. So A coup