Use of Spectral/Cepstral Analyses for Differentiating Normal From Hypofunctional Voices in Sustained Vowel and Continuous Speech Contexts

Purpose: In this study, the authors evaluated the diagnostic value of spectral/cepstral measures to differentiate dysphonic from nondysphonic voices using sustained vowels and continuous speech samples. Methodology: Thirty-two age-and gender-matched individuals (16 participants with dysphonia and 16 controls) were recorded reading a standard passage (The Rainbow Passage; Fairbanks, 1960) and sustaining the vowel /a/. Recorded voices were analyzed with custom software that calculated 4 spectral/cepstral measures. Results: Measures of cepstral peak prominence (CPP) and low-high spectral ratio (L/H ratio) were significantly different between groups in both speaking conditions; the standard deviation of the CPP was significantly different between groups in continuous speech only. In differentiating dysphonic individuals with a hypofunctional etiology from nondysphonic individuals, receiver operating characteristic (ROC) analyses demonstrated (a) high sensitivity and high specificity for the CPP in the sustained vowel condition and (b) high sensitivity and moderate specificity for the CPP in the speech condition. Conclusions: In a sample of dysphonic speakers (hypofunctional etiologies) versus typical speakers, spectral/cepstral measures of CPP and L/H ratio were able to differentiate these groups from one another in both vowel prolongation and continuous speech contexts with high sensitivity and specificity. The results of this study support the growing body of literature documenting the significant value of cepstral and other spectral-based acoustic measures to the clinical evaluation and management processes.