Speech therapy doesn't work, and, as a psychologist and stutter (or almost ex) the research in this field in lacking. In Italy I had the luck to follow a course of an ex stutter psychologist ho helps a lot of people. The focus is to unblock the thinking, to destroy the block that we feel in mind. It helps me a lot, and makes me able to graduate with the maximum points. It's a combination of muscolar work that lead to think sound to sound, and it the end you sound very natural