Comparison of biomechanical modeling of register transitions and voice instabilities with excised larynx experiments

Voice instabilities were studied using excised human larynx experiments and biomechanical modeling. With a controlled elongation of the vocal folds, the experiments showed registers with chest-like and falsetto-like vibrations. Observed instabilities included abrupt jumps between the two registers e...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2007-07, Vol.122 (1), p.519-531
Main Authors: Tokuda, Isao T., Horáček, Jaromir, Švec, Jan G., Herzel, Hanspeter
Format: Article
Language:English
Subjects:
Acoustics
Biomechanical Phenomena
Computer Simulation
Elasticity
Exact sciences and technology
Fundamental areas of phenomenology (including applications)
Humans
In Vitro Techniques
Larynx - physiology
Larynx - surgery
Models, Biological
Motion
Phonation - physiology
Physics
Reproducibility of Results
Sound Spectrography
Speech Acoustics
Vibration
Vocal Cords - physiology
Voice - physiology
Voice Disorders - physiopathology
Voice Quality
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Summary:Voice instabilities were studied using excised human larynx experiments and biomechanical modeling. With a controlled elongation of the vocal folds, the experiments showed registers with chest-like and falsetto-like vibrations. Observed instabilities included abrupt jumps between the two registers exhibiting hysteresis, aphonic episodes, subharmonics, and chaos near the register transitions. In order to model these phenomena, a three-mass model was constructed by adding a third mass on top of the simplified two-mass model. Simulation studies showed that the three-mass model can vibrate in both chest-like and falsetto-like patterns. Variation of tension parameters which mimic activities of laryngeal muscles could induce transitions between both registers. For reduced prephonatory areas and damping constants, extended coexistence of chest and falsetto registers was found, in agreement with experimental data. Subharmonics and deterministic chaos were observed close to transitions between the registers. It is concluded that the abrupt changes between chest and falsetto registers can be understood as shifts in dominance of eigenmodes of the vocal folds.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.2741210