Acoustical outcomes of a behavioral voice treatment program targeting breathiness in essential vocal tremor

Essential vocal tremor (EVT) affects up to 62% of the 25 million people diagnosed with essential tremor worldwide. EVT is characterized by modulation of the fundamental frequency (fo ) and intensity, which leads to a shaky voice and impairs quality of life. Medical treatment has inconsistent benefits and adverse effects for speakers with EVT. However, simulation studies and case studies indicate that behavioral treatment targeting a breathier voice may reduce listeners’ perception of shakiness and improve acoustical measures of EVT. In contrast, a recent single-case experiment using a single session withdrawal design showed conflicting findings. The current study examined the acoustical effects of a 6-week voice treatment program systematically training breathiness in two female participants with EVT using a single-case experiment with a multiple baselines design. Participants completed a pre-treatment assessment, 5–10 baseline sessions, and 12 remote treatment sessions with certified speech-language pathologists. Acoustical analyses were completed by two blinded assessors to measure the rate and extent of fo and intensity modulation. Standard visual analyses for single-case experiments revealed a reduction in the intensity modulation rate for one participant and the fo modulation rate for the other participant. Mixed-effects modeling in R will be conducted to evaluate treatment-related changes.