NEW YORK/ATLANTA (Reuters) – As the U.S. Federal Reserve’s chief communicator, Chair Janet Yellen is under building pressure among her colleagues and global investors to clarify where the world’s biggest central bank is heading and how it is making its decisions. The calls have come from both her policy opponents like St. Louis Fed President James Bullard and more centrist sympathizers like Atlanta Fed President Dennis Lockhart, as well as market analysts and investors who say they have been confused about the Fed’s direction.