Cepstral measures in the assessment of severity of voice disorders

To analyze whether there is an association between the presence, intensity and type of voice disorder and the cepstral measures in samples of individuals with voice complaints.

We used 376 vowel /Ɛ/ samples from individuals of both genders that had voice complaints. An analogue-visual scale was used for the auditory-perceptual analysis of voices regarding the overall grade of dysphonia (G) and the grades of roughness (R), breathiness (B), and strain (S), including a determination of voice quality (rough, breathy or strained). Measures related to cepstral peak prominence smoothed (CPPS) and spectral decline of vocal samples were extracted.

There were differences in the CPPS values between the groups with or without voice disorders as well as between the different intensities and types of voice disorder. CPPS values were lower because of the presence and intensity of voice disorders. The CPPS values differentiated the following voices: rough x breathy, rough x strained, and breathy x strained. The spectral decline only differentiated breathy x strained voices. CPPS correlated positively and strongly with G and B; moderately and negatively with R, and negatively and weakly with S. The spectral decline had a moderate positive correlation with S and a weak negative correlation with B.

There is association between voice disorder, G, predominant voice quality, and CPPS. In particular, G is strongly correlated with CPPS. Spectral decline is associated only with the parameters B and S.