Clinical Usefulness of Cepstral Analysis in Dysphonia Evaluation

Park, Min Chul; Mun, Myung Ki; Lee, Sang Hyuk; Jin, Sung Min

Abstract

BACKGROUND AND OBJECTIVES
With the present methods for assessing speech, there are procedures that make effective diagnostics possible for voice disorders. One such procedure is cepstrum. Spectrum is produced by Fourier transformation of sound waves, and if Fourier transformation is performed again about the spectrum, cepstrum is produced. This study compared cepstrum to jitter, shimmer, and noise-to-harmonic ratio (NHR) for assessment of its usefulness. Cepstrum was measured by Cepstral Peak Prominence (CPP) calculated by the Hillenbrand method and Cepstral Mean Values (CMV) calculated using the Computerized Speech Laboratory software.
SUBJECTS AND METHOD
We included in the study 30 patients with vocal nodule and unilateral vocal cord palsy who were diagnosed in Kangbuk Samsung Hospital between March 2010 and May 2011, and 30 normal controls. Phonation of sustained vowel /a/ sample and running speech was subjected to acoustic analysis using CMV and CPP. Then we compared the correlation of cepstrum with other acoustic methods.
RESULTS
The measured values of CPP-a were 14.16, 17.25, 20.00 and the age adjusted CPP-s values were 11.21, 12.85, 15.00 for vocal cord palsy, vocal nodule and normal group, respectively. There was significant correlation with perceptions of dysphonia (p<0.001), but in CMV-a, CMV-s, there was no significant correlation. When jitter, shimmer, and NHR were compared with cepstrum, the result showed negative correlation among the three groups but CPP values showed significant difference (p<0.001).
CONCLUSION
In the assessment of voice disorders, cepstrum may be used as a reliable method for comparing other complementary analysis tools. For the acoustic analysis of voice by cepstrum, however, CPP has more reliable correlations with dysphonia than CMV.