While there is some evidence for the effectiveness of voice therapy for transgender people, it is still weak. In a 2012 review by Oates (as referenced in Davies, Papp, and Antoni, 2015) of the literature on transgender voice therapy, 83% of studies were found to be at the lowest level of the evidence hierarchy for evidence-based practice, and the remaining 17% were also at low levels. However, research does show that transgender clients who have had voice therapy have high satisfaction with the results, and there is a strong consensus among speech language pathologists (SLPs) as to what are strong markers of speaker gender in voice.