Adaptation and Validation of Vocal Fatigue Index (VFI) to Malayalam Language.

OBJECTIVE: The purpose of the present study was to translate and validate the English version of the Vocal Fatigue Index (VFI) in to Malayalam language.

METHODS: The English version of the VFI was translated into Malayalam language using parallel back translation. The translated version was content validated by three qualified Speech Language Pathologists. The final Malayalam version of the VFI was administered on 528 primary school teachers with and without self-reporting of voice problems. The internal consistency and test-retest reliability were determined using Cronbach's alpha and intraclass correlation coefficients. Independent sample t test was used to assess the difference in means. Receiver operating characteristic curves with sensitivity and specificity were calculated to set cut-off scores for three domains of Malayalam VFI.

RESULTS: The results revealed that the Malayalam version of VFI has an excellent internal consistency across all the three factors of VFI; tiredness of voice and avoidance of voice use (α = 0.922), physical discomfort symptoms (α = 0.923), and improvement of symptoms with voice rest (α = 0.925). Independent sample t test revealed a significant difference (P ≤ 0.001) for total scores of three domains [tiredness and avoidance of voice use (factor 1), physical discomfort symptoms (factor 2), improvement in symptoms with voice rest (factor 3)] between teachers reporting voice problems and teachers not reporting voice problems. Cut-off scores for three different domains of the Malayalam VFI were set at ≥ 16.5 (80% sensitivity and 71.4% specificity) for factor 1, ≥ 6.5 (71.1% sensitivity and 70.1% specificity) for factor 2 and ≤ 7.5 (71.1% sensitivity and 69.9% specificity) for factor 3.

CONCLUSION: The Malayalam VFI was found to have good internal consistency and reliability. Hence, it can be considered as a valid and reliable tool for identifying vocal fatigue symptoms and its severity among the Malayalam speaking community who report voice disorders.