Objective: To develop and validate the Vocal Fatigue Index for Teachers (VFI-TEACH), a patient-reported outcome measure that reliably identifies vocal fatigue as an individual-specific but measurable symptom influencing vocal task performance in public school teachers.

Method: Survey/scale development and validation occurred over three major stages. In the initial qualitative phase for index generation, the original Vocal Fatigue Index underwent cognitive pre-testing with six public school teachers to explore content validity. In the second stage, 136 public school teachers across the United States completed a VFI-TEACH prototype for internal consistency testing and factor analysis. The final stage concentrated on convergent, known-groups, and predictive validities including index cut-off scores from 109 public school teacher responses. The VFI-TEACH was further validated for test-retest reliability for 41 public school teachers.

Results: Cronbach's alpha for the entire VFI-TEACH was 0.951. No further items were eliminated, resulting in a 21-item index. Three factors were extracted using principal factor analysis with oblimin rotation and Kaizer normalization: factor 1, related to vocal function; factor 2, related to vocal rest; and factor 3, related to vocal symptoms and sensations. Pearson correlation between VFI-TEACH and Voice Handicap Index-10 scores was r = 0.796 at p < 0.001. Mann Whitney U and Welch's t-test suggest that the VFI-TEACH index score could distinguish between teachers reporting no/low vocal fatigue versus high vocal fatigue as self-reported on a visual analogue scale with consideration to unequal sample size. Receiving operating characteristic (ROC) and area under the curve (AUC) analysis determined VFI-TEACH index scores between 16.5 and 18 as potential threshold/cut-offs to identify vocal fatigue in teachers. Finally, test-retest reliability for the VFI-TEACH was strong (r = 0.937, p < .001).

Conclusions: The VFI-TEACH is a validated index with good psychometric properties that is sensitive to teachers experiencing trait-level vocal fatigue. Although there are strong parallels to the original Vocal Fatigue Index, major distinctions include development methodology to include patient-respondents for content validity, a composite index score, and unique factors. Further investigation is necessary to explore the relationship between the factors as well as the VFI-TEACH's validity as a treatment outcome measure.