Have to tried distracting him - working through obedience commands instead of just letting him bark? What happens when he barks now? Do you just yell? Because that could be interpreted by him as a positive response. Some "interruption" techniques include having a spray bottle with water handy and spritzing him when he barks. Another is putting a few pebbles in a soda can, and rattling that when he barks. Whatever you decide to do, everyone in the family must do it consistently.