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Global and local dimensions of vocal dynamics
1Department of Otolaryngology and Communicative Disorders, Long Island Jewish Medical Center, New Hyde Park, New York 11040, USA.
The Journal of the Acoustical Society of America
|January 28, 1999
Summary
Healthy vocal fold vibration uses a low-dimensional space, while pathology can introduce complexity. However, even irregular vocal fold dynamics are often governed by a low number of degrees of freedom.
Area of Science:
- Voice production
- Biophysics
- Nonlinear dynamics
Background:
- Vocal fold vibration analysis is crucial for understanding voice disorders.
- Nonlinear dynamics offer tools to analyze complex physiological signals.
Purpose of the Study:
- To investigate the dimensionality of vocal fold dynamics in healthy and pathological phonation.
- To compare global embedding dimension (dE) and local dynamical dimension (dL) between groups.
Main Methods:
- Analysis of microphone and electroglottographic (EGG) signals during sustained /a/ phonation.
- Calculation of global embedding dimension (dE) and local dynamical dimension (dL).
- Segmentation of data into periodic and irregular segments for pathological subjects.
Main Results:
- Healthy subjects consistently showed a low-dimensional attractor (dL=3) and small embedding dimension (dE).
- Pathological subjects often exhibited higher-dimensional components (dE), but local dynamics (dL) remained low-dimensional.
- No consistent differences in degrees of freedom were found between healthy and pathological phonation, except in severe breathiness.
Conclusions:
- Vocal fold dynamics, even when irregular in pathology, are largely governed by a low number of degrees of freedom.
- Global embedding dimension (dE) may increase with pathology, but local dynamics (dL) remain constrained.
- Nonlinear analysis techniques can effectively characterize vocal fold dynamics despite signal noise.