Translation and Adaptation of the Vocal Fatigue Index into Spanish

Aim: the purpose of this study was to translate and adapt the English version of the Vocal Fatigue Index (VFI) into the Spanish language. Methods: the English version of the Vocal Fatigue Index (VFI) was translated into Spanish by two bilingual speech-language pathologists, and then was back-translated into English. The Spanish VFI (o “Indice de Fatiga Vocal”, IFV) was administrated to a pilot group of 10 individuals, which revealed some small typographical and grammatical adjustments to the index. The final updated version was then administrated to 34 subjects (21 with voice disorders, and 13 without voice disorders). Internal consistency and scale reliability were analyzed using Cronbach alpha coefficient. Results: a high Cronbach alpha coefficient for the three factors (0.87) was obtained. The results of the item role in reliability of the Spanish VFI demonstrated that all of them showed a positive role according to this criterion. The results of the ANOVA indicate a statistically significant difference between groups on the three scores of the Spanish translation of the VFI. In comparison to the healthy participants, those with voice disorders obtained statistically significant higher scores for the Spanish VFI subscales. Conclusion: the present study suggests that the Spanish translation of the Vocal Fatigue Index has a good internal consistency and high reliability on each of the three factors. The results suggest that the Spanish VFI can be used reliably to identify persons with vocal fatigue and has good clinical validity.