Nonlinear Source-Filter Coupling Due to the Addition of a Simplified Vocal Tract Model for Excised Larynx Experiments

作者：Smith Benjamin L; Nemcek Steven P; Swinarski Krzysztof A; Jiang Jack J^*

来源：Journal of Voice, 2013, 27(3): 261-266.

DOI：10.1016/j.jvoice.2012.12.012

• Vocal tract
• Supra glottal structure
• Source-filter coupling
• Phonation threshold pressure
• Excised larynx

Objectives. Traditional excised larynx dissection and setup calls for the removal of all supraglottal structures, eliminating any source-filter interactions that measurably affect the acoustic properties of phonation. We introduce a simplified vocal tract model that can be used in the excised larynx experiments and tested the nonlinear source-filter interactions that are present with the addition of highly coupled, supraglottal structures.
Methods. Aerodynamic and acoustic data were measured at phonation threshold pressure (PTP) and +25% PTP in 10 excised canine larynges using a modified dissection technique. PTP and phonation threshold flow (PTF) were defined as the pressure and flow at the phonation onset; phonation threshold power (PTW) is the product of these values. Data were recorded for four experimental conditions: PTP without vocal tract; +25% PTP without vocal tract; PTP with vocal tract; and +25% PTP with vocal tract. Differences in PTP, PTF, and PTW were evaluated. For trials conducted at +25% PTP, differences in airflow were evaluated.
Results. PTP (P = 0.009) and PTW (P = 0.002) were significantly reduced with the addition of the novel vocal tract. A reduction in PTF was also present with the vocal tract (P = 0.021), but airflow was not significantly reduced in +25% PTP trials (P = 0.196).
Conclusion. The proposed vocal tract can be used with complete larynges when conducting excised larynx experiments. The effects of nonlinear source-filter interaction were observed during trials with the vocal tract, as evidenced by changes in threshold aerodynamic parameters.

• 出版日期2013-5