Reliability and validity of the Turkish version of the vocal fatigue index

The aim of this study is to evaluate the reliability and validity of the Turkish version (SYO) of the Vocal Fatigue Index measure. The first step was performed with two independent translators for the translation of the original VFI measure from English to Turkish. The translated scales were combined by two experienced specialists in the field and a common translation scale was created. The created scale was converted back to English by another translator and the final scale was obtained. The study was conducted with 535 patients including 285 voice complaints, and 250 with no complaints. Voice-Related Quality of Life (V-RQOL) scale was administered to the participants with Turkish version of VFI in 5-15 days as a test-retest. Cronbach alpha internal consistency coefficient and test-retest reliability coefficients were calculated for reliability evaluation. The structural validity of VFI was calculated by Pearson's correlation coefficient test and the strength of the correlation with V-RQOL was evaluated. The Cronbach's alpha coefficient of VFI was found to be 0.920 for fatigue and avoidance, 0.879 for physical discomfort, and 0.882 for improvement with rest. The test-retest reliability revealed 0.877 for the fatigue and avoidance, 0.913 for the physical discomfort, and 0.820 for the improvement with rest. The mean total scores of V-RQOL were significantly decreased with increased vocal fatigue factor scores (r =-0.809, r =-0.512 and p <0.001, r =-0.147, and p <0.05). When compared with individuals without complaints, VFI factor scores were found to be decreased with statistical significance in patients with complaints (p <0.001). According to the findings, it was shown that the Turkish version of VFI is reliable and valid and it can be used as a useful measurement tool to evaluate vocal fatigue Key Words: Voice; Fatigue; Reliability; Validity; Measure, Quality of Life