Cepstral and Perceptual Investigations of Voice in Speech and Language Pathologists with Vocal Fatigue

Vocal fatigue is known as a hyperfunctional voice disorder that can lead to other conditions, such as muscle tension dysphonia (MTD). Speech and language pathologists (SLPs) are professional voice users who may suffer from vocal fatigue due to heavy vocal demands. This study aimed at investigating the cepstral and perceptual dimensions of voice and their correlation in the SLPs with vocal fatigue. Twenty-six SLPs and senior speech therapy students (mean age = 27.11 ± 6.8 yrs), including men (n = 5) and women (n = 21), participated in this descriptive cross-sectional study. They had vocal fatigue according to the Vocal Fatigue Index (VFI). In acoustic assessment, cepstral analysis (CPP and CPPS) was performed using Praat software. The Persian version of Consensus Auditory Perceptual Evaluation of Voice (CAPE-V) was used to evaluate the overall severity of dysphonia. The correlation between these two evaluations was also investigated using IBM SPSS Statistics software version 23. Results revealed that the mean CPPS (13.716 ± 2.084) was lower than the cutoff point. Perceptual findings indicated that the mean overall severity (10.557 ± 11.210) fell in the normal variability of voice quality (NVVQ) range. In addition, cepstral and perceptual evaluations had no significant correlation (P > 0/05). The findings showed that auditory-perceptual evaluation considered the gold standard method of voice evaluation, cannot solely identify vocal fatigue. However, cepstral measures can help provide a more objective profile of vocal function in SLPs with vocal fatigue. Therefore, both of these evaluations are recommended for voice assessment of vocal fatigue.