Spectral- and cepstral-based acoustic features of dysphonic, strained voice quality

Objectives: We sought to determine whether spectral- and cepstral-based acoustic measures were effective in distinguishing dysphonic-strained voice quality from normal voice quality and whether these measures were related to auditory-perceptual ratings of strain severity. Methods: Voice samples from 23 speakers with dysphonia characterized predominantly by strained voice quality and 23 speakers with normal voice were acoustically analyzed. Measures related to the prominence of the cepstral peak and the ratio of low- to high-frequency spectral energies, as well as the variation of each, were computed from continuous speech and a sustained vowel. Correlations to perceptually rated strain severity were determined. Results: Measures related to the cepstrum were the strongest discriminators between dysphonic-strained voice and normal voice. Variation in the ratio of low- to high-frequency spectral energies also significantly differentiated the two speaker groups. All measures were significantly correlated with perceptually rated strain severity, including an acoustic severity index that incorporated both cepstral- and spectral-based measures. Conclusions: Cepstral- and spectral-based measures that have been previously studied in dysphonia characterized by breathiness and roughness are effective in distinguishing strained dysphonia from normal voice quality. The utility of these acoustic measures is supported by their moderate-to-high relationship with perceptually rated strain severity.