Cepstral analysis of voice in unilateral adductor vocal fold palsy

Unilateral vocal fold paralysis (UVFP) occurs because of the dysfunction of the vagus nerve innervating the larynx. It causes a characteristic breathy voice often accompanied by swallowing disability, a weak cough, and the sensation of shortness of breath. Clinical evaluation of voice is generally based on perceptive criteria and the acoustic analysis of voice. In the present study, it is hypothesized that there would be an abnormal reduction of the cepstral peak in speakers with UVFP relative to the normal controls, as they are characterized by a breathy voice because of inadequate closure of vocal folds.

Phonation of sustained vowel /a/ sample was subjected to acoustic analysis using Computerized Speech Lab (CSL model 4150; Kay Pentax, Lincoln Park, NJ) software. The vowels were analyzed acoustically by the measurement of cepstral peak prominence (CPP).

The results of 2 × 2 analysis of variance revealed the main effects of the groups (clinical vs control group), indicating reduced cepstral peak value in the clinical group in comparison with controls. The main effect of gender was also significant, indicating a decrease in the CPP value in the female group in comparison with the male group. The results obtained were discussed with respect to the underlying pathophysiology.

The present study investigated the CPP in subjects with UVFP. Cepstral deviations in the clinical group are explained to be the result of the presence of phonatory gap, leading to the lower values of CPP.