Energy distribution analysis and nonlinear dynamical analysis of adductor spasmodic dysphonia

The present study investigated the voice quality associated with adductor spasmodic dysphonia by means of various acoustical measures. Energy distribution analyses and nonlinear dynamical measurements were used to depict the differences among voices associated with adductor spasmodic dysphonia (ADSD), vocal nodules (VN) and normal voices. Possible acoustical differences between voices associated with unilateral vocal fold paralysis (UVFP) and ADSD, UVFP and normal voice were investigated. Noise-to-harmonic ratio (NHR), harmonic-to-noise ratio (HNR), glottal-to-noise excitation (GNE), empirical mode decomposition excitation ratio (EMD-ER), nonlinear recurrence period density entropy (RPDE), detrended fluctuation analysis (DFA), correlation dimension (D2), and permutation entropy (PE) values were obtained from the sustained vowel /a/ produced by the subjects. Results revealed high specificity of these acoustic measures in distinguishing the voice quality of ADSD, VN, and UVFP voices from normal voices. In addition, combining GNE and D2 measures appears to be effective in distinguishing ADSD from normal and VN voices.