title: Voicing produced by a constant velocity lung source.
abstract: An investigation is made of the influence of subglottal boundary conditions on the prediction of voiced sounds. It is generally assumed in mathematical models of voicing that vibrations of the vocal folds are maintained by a constant subglottal mean pressure pI, whereas voicing is actually initiated by contraction of the chest cavity until the subglottal pressure becomes large enough to separate the vocal folds. The problem is reformulated to determine voicing characteristics in terms of a prescribed volumetric flow rate Qo of air from the lungs-the evolution of the resulting time-dependent subglottal mean pressure p[overline]-(t) is then governed by glottal mechanics, the aeroacoustics of the vocal tract, and the influence of continued contraction of the lungs. The new problem is analyzed in detail for an idealized mechanical vocal system that permits precise specification of all boundary conditions. Predictions of the glottal volume velocity pulse shape are found to be in good general agreement with the traditional constant-pI theory when pI is set equal to the time averaged value of p[overline]-(t). But, in all cases examined the constant-pI approximation yields values of the mean flow rates Qo and sound pressure levels that are smaller by as much as 10%.
authors.affiliation: Boston University, College of Engineering, 110 Cummington Mall, Boston, Massachusetts 02215, USA. mshowe@bu.edu
authors.forename: M S
authors.initials: MS
authors.lastname: Howe
authors.forename: R S
authors.initials: RS
authors.lastname: McGowan
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005931:Glottis / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000502:physiology*; D008954:Models, Biological; D009119:Muscle Contraction; D009716:Numerical Analysis, Computer-Assisted; D010699:Phonation; D011312:Pressure; D012132:Respiratory Muscles / Q000502:physiology; D013997:Time Factors; D014732:Vibration; D014831:Voice
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