The Validity of Cepstral Analysis to Distinguish Between Different Levels of Perceptual Dysphonia in the Persian Vocal Tasks.

Objectives/hypothesis: The validity of cepstral analysis (Cepstral Peak Prominence [CPP] and Cepstral Peak Prominence-Smoothed [CPPS]) as an indicator of perceptual dysphonia was investigated in the Persian language STUDY DESIGN: Cross-sectional study.

Methods: A total of 223 participants (159 with and 64 without dysphonia) uttered vowels /a/ and /i/, six standard sentences, and non-standard connected speech. All vocal samples were perceptually evaluated by three raters on a visual analog scale and put into four groups (normal voice, mild, moderate, and severe perpetual dysphonia). CPP and CPPS of sustained vowel /a/, reading the second standard sentence, and a sentence extracted from non-standard connected speech were established using "Praat" software. Statistical analysis involved a one-way factorial analysis of variance (ANOVA), Kruskal-Wallis H, Kendall's Tau-b correlation, t test, and receiver operating characteristics (ROC) curve.

Results: The results showed that CPP of sustained vowels and reading the standard sentence and CPPS of sustained vowel differed significantly (P < 0.05), except between the normal voice and mild perpetual dysphonia groups (P > 0.05). The CPP of non-standard connected speech, CPPS of reading the standard sentence, and non-standard connected speech differed significantly between all groups (P < 0.05). The mean of cepstral analysis of all tasks, "averaged CPP," and "averaged CPPS" were significantly different between two groups of the normal voice and perceptual dysphonia (P < 0.05). Correlation between the cepstral analysis and the perceptual ratings demonstrated that the correlation coefficients for CPP and CPPS were between 0.4 and 0.6 (P < 0.05). ROC curve analysis revealed that the area under the ROC curve for "averaged CPP" and "averaged CPPS" was greater than 0.8 (P < 0.05). The values of 22.11 and 12.29 were determined as cut-off scores of "averaged CPP" and "averaged CPPS," respectively.

Conclusions: Cepstral analysis was known as useful clinical tool for diagnosis of perpetual dysphonia and determining its severity level in the Persian language.