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

Abstract

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 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 ten 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; +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.

New Evidence That Nonlinear Source-Filter Coupling Affects Harmonic Intensity and fo Stability During Instances of Harmonics Crossing Formants

“…10, 11 Additionally, interaction has been observed in the form of f o jumps and the presence of subharmonics with acoustic coupling to the subglottal system 12 as well as in excised canine and porcine larynges with an added supraglottal vocal tract. 13, 14 …”

A novel method for early diagnosis of Alzheimer’s disease based on higher-order spectral estimation of spontaneous speech signals

“…The neural control of the glottal pulse system exhibits the complex nonlinear behavior, with nonlinear interactions r because physiological conditions would most likely involve autonomic nervous system regulation based on a dynamic simultaneous activity of the human speech responses to physical environmental stresses (Smith et al 2013).…”

Skewing of the glottal flow with respect to the glottal area measured in natural production of vowels

“…The majority of the previous studies on source-filter interaction are based on theoretical modeling of voice production and computer simulations. In addition, other approaches such as excised larynx experiments have been adopted in studying, for example, the effect of sourcefilter coupling on phonation threshold pressure (e.g., Smith et al, 2013). Source-filter interactions have also been studied in natural production of speech, but only a few of these studies have focused on glottal flow skewing.…”