The Voice Symptom Scale (VoiSS) and the Vocal Handicap Index (VHI): a comparison of structure and content.

Self report measures of voice function are in frequent use, but have had inadequate psychometric evaluation. We aimed to perform a substantial factor analysis of two measures of voice impairment, the Voice Symptom Scale (VoiSS) and the Voice Handicap Index (VHI). Both the 30-item questionnaires were completed by 319 dysphonic voice clinic attenders (99M, 220F). Principal components analysis confirmed that both instruments reflected general voice abnormality. The VoiSS comprised three factors - impairment (15 items), emotional (8 items) and related physical symptoms (7 items) - each with a good internal consistency. Analysis of the VHI suggested that it contains only two subscales. When a three-factor solution was imposed on the data, analysis failed to support the currently advised three 10-item subscale interpretations. Instead, we found a physical (voice impairment) domain (8 items), a psychosocial domain (14 items) and a factor with 8 items related to difficulty in being heard. The VHI requires further statistical refinement to identify its subscale structure. The VoiSS was developed from 800 subjects and is psychometrically the most robust and extensively validated self report voice measure available.