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