The effect of glottal opening on the acoustic response of the vocal tract

Barney, Anna, De Stefano, Antonio and Henrich, Nathalie (2005) The effect of glottal opening on the acoustic response of the vocal tract. European Acoustics Association Forum Acusticum 2005 Conference, Budapest. 28 Aug - 01 Sep 2005. 6 pp .

Abstract

In the source-filter model of speech production it is assumed that the acoustic source mechanism is independent of the vocal tract acoustics. In fact, the changing acoustic boundary condition at the glottal end of the vocal tract may be expected to affect the formant frequency and the formant bandwidth, with a corresponding effect on voice quality.
In this study, a geometrically simplified physical model of the vocal tract, larynx and sub-glottal tract is used in the presence of an external applied sound field to quantify the changes to the acoustic response of the vocal tract with changing glottal width. The applied sound field is tonal, generated by a loudspeaker, at frequencies ranging from 100 Hz to 2 kHz. The acoustic response of the vocal tract is measured with a pair of pressure transducers, spaced 8 cm apart, and mounted flush with the vocal tract wall. The acoustic transfer function from glottis to lips of the vocal tract is calculated from the measurements using the method described by Holland and Davies (JSV, 230(4), 915-932, 2000) and shows an increase in the first formant frequency of the order of 13% at F1 when the glottis is open to a width of mm compared to the closed-glottis case.
The experimental measurements will be compared to a theoretical model that takes the change in glottal impedance with changing glottal width into account.

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Contributors

Author: Anna Barney

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