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Measurements of glottal structure dynamics
John F Holzrichter1, Lawrence C Ng, Gerry J Burke
1Lawrence Livermore National Laboratory, Livermore, California, USA. holzrichter1@llnl.gov
The Journal of the Acoustical Society of America
|April 6, 2005
Summary
Electromagnetic (EM) wave sensors accurately measure vocal fold movements during speech. Trachea wall movements contribute minimally to EM sensor signals, clarifying their application in speech technology.
Area of Science:
- Biomedical Engineering
- Acoustics
- Speech Science
Background:
- Low power, radarlike electromagnetic (EM) wave sensors are used to measure human vocal tract tissue motion during speech.
- An uncertainty exists regarding the source of EM sensor signals in the laryngeal region: vocal fold movement vs. trachea wall movement.
Purpose of the Study:
- To differentiate contributions from vocal fold and trachea wall movements to EM sensor signals.
- To validate the efficacy of EM sensors for measuring vocal fold dynamics.
Main Methods:
- Experiments were conducted with a tracheostomized subject capable of phonation.
- Laser-doppler measurements assessed posterior trachea tissue movement.
- Electromagnetic (EM) wave sensors and air-pressure measurements were utilized.
- 3-D EM wave simulations were performed.
Main Results:
- Posterior trachea wall movements (approx. 15 microns) showed insignificant contribution to EM sensor signals.
- Anterior trachea wall movements did contribute to the signals.
- EM sensors effectively measured vocal fold movements, supported by simulations.
- Simulations revealed EM wave guiding across the vocal fold membrane, interrupted by glottal opening.
Conclusions:
- Electromagnetic (EM) wave sensors accurately capture vocal fold movements.
- Trachea wall movements have a limited impact on the signals from current EM sensors.
- These findings support EM sensor applications in speech de-noising, vocoding, recognition, and diagnostics.