Stuttering is a neurological problem where the person hearing his own speech interacts improperly with the brain mechanism causing us to stutter. When we do not hear our own speech we stutter less. This is why we stutter less when we whisper, sing or speak in unison with another person. What has helped me is programs where I do not hear my own speech. The McGuire program and similar programs which change your breathing and speech are wonderful. Similarly stuttering devices like the Edinburgh Masker or Delayed Auditory Feedback (DAF) where you hear your speech either Masked or Delayed are often very helpful.