Simple models; complex flows
Barney, A (2010) Simple models; complex flows. In, 9th International Conference on Advances in Quantitative Laryngology, Voice and Speech Research, Erlangen, DE, 10 - 11 Sep 2010.
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Introduction: Advances in computational fluid dynamic (CFD) modelling allow ever more sophisticated models of the fluid flow in the larynx to be produced (e.g. Horáček and Gráf, 2009). More recently, the ability to couple models between multiple physical domains has allowed fluid models to interact with dynamic tissue models and/or with models of acoustic generation (e.g. Zörner et al., 2009). The ability to model abrupt features, both temporal (such as glottal closure) and spatial (such large area changes) is less well developed. It is interesting to explore the effect that small geometric changes may have on a flow field and its sound generating properties to try to evaluate the sensitivity of speech flow regimes to approximations in the channel shape.
Methods: Measurements made on a dynamic mechanical model of the vocal folds and tract (Barney and Jackson, 2009) have been used to investigate the sensitivity of the hydrodynamic and acoustic fields to small changes in the tract geometry. Pressure at the duct wall in the model vocal tract and radiated SPL at the model lips were measured while an oscillating flow interacted with an orifice plate and a down-stream obstacle. The effect of small changes in the relative location of the geometric features on the fluid behaviour and acoustic output was observed.
Results: The interaction between the fluid motion and the geometric features was highly dependent on their relative configuration, with a corresponding sensitive dependence regarding the generation of sound. Complex interactions between the fields developed from relatively simple structural combinations.
Discussion: When modelling flow regimes within the larynx and vocal tract we need to be aware that even slight approximations in the geometric specification of the duct can have significant and complex effects on the hydrodynamic and acoustic fields and their interaction. Comparison of outputs from CFD models where duct geometries are an approximation to the real shape with the fluid behaviour in the in vivo vocal tract is therefore challenging. Rather than looking for absolute models of flow fields, a more productive paradigm may be to use CFD models to answer specific questions about the effect of geometric change on the flow and acoustic fields and their interaction.
|Item Type:||Conference or Workshop Item (Paper)|
|Subjects:||R Medicine > RF Otorhinolaryngology
Q Science > QA Mathematics
|Divisions:||University Structure - Pre August 2011 > Institute of Sound and Vibration Research > Signal Processing and Control
|Date Deposited:||23 Sep 2010 15:06|
|Last Modified:||02 Mar 2012 13:37|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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