If ya don't do what Magnum thinks should be done, you get a loud, quick exhale out through his nose, like he's disgusted with you. When you come home, you might, if you're lucky, get an ears-back roo (everybody who knows him seems to live for that sound). Then ya sometimes get what I call the frustration whine when he wants to get at something and can't (usually followed by the disgust exhale, 'cause you won't let him get at what he wants to get at). Then, of course, there's the "I DIDN'T EXPECT THAT" scream which startles everybody!
Barking aside, Magnum is the noisiest dog I've every had!