About: The Fluency Master device amplified bone-transmitted phonation. The device is no longer available.
Evidence: One clinical trial was presented at a conference. The device reduced stuttering 14% in conversation without therapy. It was more effective for reading aloud, and when used with therapy.
References: Webster, R. (1991). Manipulation of vocal tone: implications for stuttering. In Peters, H., Hulstijn, W., & Starkweather, W. (Ed.), Speech Motor Controls and Stuttering. New York, NY: Elsevier.