I know exactley the sound you are reffering to. It is a hard sound to descibe but I have heard it many times. It is a doe. Anytime I have heard a doe make that sound she has had fawns with her are been in a large heard. I really believe it is a warning to the heard or fawn. It is definately diffrent than the sound of a dow blowing, its more like a barking noise. I can almost assure you, once you here that noise, you won't be seing any deer in that spot for a few hours at least.