Just because I have music playing does not mean that I'm welcoming people to interrupt me while I'm writing, thanks. Maybe take the biggest hint (which is a pretty obvious hint of someone focusing on a computer and a word processor and typing quite a lot) and all the small ones (short answers and responses) and go away unless it's necessary.
Which so far it hasn't been.
(I think this call for attention would also be tolerable if he'd actually stop doing it when I'm working on things. He never bothers me unless I'm working on something, and it makes me insane.)