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

Abstract

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.