1. Duke Voice Care Center, Division of Otolaryngology-Head & Neck Surgery; Duke University Medical Center; Durham North Carolina
2. Duke Clinical Research Institute; Durham North Carolina
3. Division of Public Health & Study Design and Biostatistics Center; University of Utah; Salt Lake City Utah
4. Department of Communication Sciences and Disorders, Division of Otolaryngology-Head & Neck Surgery (Adjunct); University of Utah, Salt Lake City; Utah U.S.A.