title: Nonlinear source-filter coupling due to the addition of a simplified vocal tract model for excised larynx experiments.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Otolaryngology - Head and Neck Surgery, Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Smith
authors.forename: Steven P
authors.initials: SP
authors.lastname: Nemcek
authors.forename: Krzysztof A
authors.initials: KA
authors.lastname: Swinarski
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Jiang
mesh_terms: D000162:Acoustics; D000818:Animals; D001696:Biomechanical Phenomena; D004210:Dissection; D004285:Dogs; D007825:Laryngectomy; D007830:Larynx / Q000033:anatomy & histology / Q000502:physiology* / Q000601:surgery; D008953:Models, Anatomic; D008954:Models, Biological; D015233:Models, Statistical; D017711:Nonlinear Dynamics; D010699:Phonation; D011312:Pressure; D014827:Vocal Cords / Q000033:anatomy & histology / Q000502:physiology* / Q000601:surgery