ignoring is a long process. ignoring means no reaction at all. this is really difficult but most effective. as you mentioned he starts barking even louder. this is part of the process. he'll increas the behavior to get a reaction and if you keep it up it will dissapear. but you'll need to ignore for a long time until he stops. don't even look at him as this is also a reaction..... leaving the room is the easiest way of ignoring. come back when he has stopped. if he starts leave again. he is chalanging you!