When I was in speech therapy we used one of those delayed auditory feedback devices, and it really helped me. I had been thinking for a long time about getting one of those devices until one day I discovered the app 'DAF Delayed Auditory Feedback' or 'DAF Jammer.' The app basically works the same way as those profesional devices; you just need your basic headphones. You set the app to match your speaking tempo, and that's it. This hack saved me in college, especially during presenting and oral exams.