Numerical investigation of effects of incisor angle on production of sibilant /s/

Abstract The effects of the inclination angle of the incisor on the speech production of the fricative consonant /s/ was investigated using an implicit compressible flow solver. The hierarchical structure grid was applied to reduce the grid generation time for the vocal tract geometry. The airflow a...

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Main Authors: HsuehJui Lu, Tsukasa Yoshinaga, ChungGang Li, Kazunori Nozaki, Akiyoshi Iida, Makoto Tsubokura
Format: Article
Language:English
Published: Nature Publishing Group 2021-08-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-021-96173-2
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spelling doaj-c4ab67af469344e2a877e721e42ca0942021-08-22T11:25:09ZengNature Publishing GroupScientific Reports2045-23222021-08-0111111110.1038/s41598-021-96173-2Numerical investigation of effects of incisor angle on production of sibilant /s/HsuehJui Lu0Tsukasa Yoshinaga1ChungGang Li2Kazunori Nozaki3Akiyoshi Iida4Makoto Tsubokura5Computational Fluid Dynamics Laboratory, Department of Computational Science, Graduate School of System Informatics, Kobe UniversityToyohashi University of TechnologyComputational Fluid Dynamics Laboratory, Department of Computational Science, Graduate School of System Informatics, Kobe UniversityOsaka University Dental HospitalToyohashi University of TechnologyComputational Fluid Dynamics Laboratory, Department of Computational Science, Graduate School of System Informatics, Kobe UniversityAbstract The effects of the inclination angle of the incisor on the speech production of the fricative consonant /s/ was investigated using an implicit compressible flow solver. The hierarchical structure grid was applied to reduce the grid generation time for the vocal tract geometry. The airflow and sound during the pronunciation of /s/ were simulated using the adaptively switched time stepping scheme, and the angle of the incisor in the vocal tract was changed from normal position up to 30°. The results showed that increasing the incisor angle affected the flow configuration and moved the location of the high turbulence intensity region thereby decreased the amplitudes of the sound in the frequency range from 8 to 12 kHz. Performing the Fourier transform on the velocity fluctuation, we found that the position of large magnitudes of the velocity at 10 kHz shifted toward the lip outlet when the incisor angle was increased. In addition, separate acoustic simulations showed that the shift in the potential sound source position decreased the far-field sound amplitudes above 8 kHz. These results provide the underlying insights necessary to design dental prostheses for the production of sibilant fricatives.https://doi.org/10.1038/s41598-021-96173-2
collection DOAJ
language English
format Article
sources DOAJ
author HsuehJui Lu
Tsukasa Yoshinaga
ChungGang Li
Kazunori Nozaki
Akiyoshi Iida
Makoto Tsubokura
spellingShingle HsuehJui Lu
Tsukasa Yoshinaga
ChungGang Li
Kazunori Nozaki
Akiyoshi Iida
Makoto Tsubokura
Numerical investigation of effects of incisor angle on production of sibilant /s/
Scientific Reports
author_facet HsuehJui Lu
Tsukasa Yoshinaga
ChungGang Li
Kazunori Nozaki
Akiyoshi Iida
Makoto Tsubokura
author_sort HsuehJui Lu
title Numerical investigation of effects of incisor angle on production of sibilant /s/
title_short Numerical investigation of effects of incisor angle on production of sibilant /s/
title_full Numerical investigation of effects of incisor angle on production of sibilant /s/
title_fullStr Numerical investigation of effects of incisor angle on production of sibilant /s/
title_full_unstemmed Numerical investigation of effects of incisor angle on production of sibilant /s/
title_sort numerical investigation of effects of incisor angle on production of sibilant /s/
publisher Nature Publishing Group
series Scientific Reports
issn 2045-2322
publishDate 2021-08-01
description Abstract The effects of the inclination angle of the incisor on the speech production of the fricative consonant /s/ was investigated using an implicit compressible flow solver. The hierarchical structure grid was applied to reduce the grid generation time for the vocal tract geometry. The airflow and sound during the pronunciation of /s/ were simulated using the adaptively switched time stepping scheme, and the angle of the incisor in the vocal tract was changed from normal position up to 30°. The results showed that increasing the incisor angle affected the flow configuration and moved the location of the high turbulence intensity region thereby decreased the amplitudes of the sound in the frequency range from 8 to 12 kHz. Performing the Fourier transform on the velocity fluctuation, we found that the position of large magnitudes of the velocity at 10 kHz shifted toward the lip outlet when the incisor angle was increased. In addition, separate acoustic simulations showed that the shift in the potential sound source position decreased the far-field sound amplitudes above 8 kHz. These results provide the underlying insights necessary to design dental prostheses for the production of sibilant fricatives.
url https://doi.org/10.1038/s41598-021-96173-2
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