Voice production model integrating boundary-layer analysis of glottal flow and source-filter coupling

Kaburagi, Tokihiko

doi:10.1121/1.3533732

Cited by 9 publications

(16 citation statements)

References 30 publications

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“…In this study, we used the consolidated acoustic tube model of the vocal tract, the glottis, and the subglottis based on the acoustic tube model described above. Figure 1 shows a schematic view of the connected acoustic tube model [8]. (A0, B0, C0, D0), (A1, B1, C1, D1), and (Ag, Bg, Cg, Dg) represented the propagation coefficients of the subglottis, the vocal tract, and the glottis, respectively.…”

Section: Acoustic Tube Model In the Concatenation Of The Vocal Tractmentioning

confidence: 99%

A Simulation Study on the Effect of Glottal Boundary Conditions on Vocal Tract Formants

Uezu

Kaburagi²

2017

Interspeech 2017

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In the source-filter theory, the complete closure of the glottis is assumed as a glottal boundary condition. However, such assumption of glottal closure in the source-filter theory is not strictly satisfied in actual utterance. Therefore, it is considered that acoustic features of the glottis and the subglottal region may affect vocal tract formants. In this study, we investigated how differences in the glottal boundary conditions affect vocal tract formants by speech synthesis simulation using speech production model. We synthesized five Japanese vowels using the speech production model in consideration of the source-filter interaction. This model consisted of the glottal area polynomial model and the acoustic tube model in the concatenation of the vocal tract, glottis, and the subglottis. From the results, it was found that the first formant frequency was affected more strongly by the boundary conditions, and also found that the open quotient may give the formant stronger effect than the maximum glottal width. In addition, formant frequencies were also affected more strongly by subglottal impedance when the maximum glottal area was wider.

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Section: Acoustic Tube Model In the Concatenation Of The Vocal Tractmentioning

confidence: 99%

A Simulation Study on the Effect of Glottal Boundary Conditions on Vocal Tract Formants

Uezu

Kaburagi²

2017

Interspeech 2017

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“…On the basis of the IBL analysis [10,11,15,17], a method is presented in this section to analyze the behavior of glottal flow passing through an asymmetrical channel. For flow that has a high Reynolds number, the core flow region outside the boundary layer can be considered as inviscid, while the effect of air viscosity is apparent in the vicinity of the wall of the channel and in the wake.…”

Section: Boundary-layer Analysis Of Glottal Flow In An Asymmetrical Cmentioning

confidence: 99%

“…The boundary-layer equations, Eqs. (12) through (15), are separated for each vocal fold, while the core flow relations, Eqs. (16) and (17), are coupled by the displacement thicknesses, L and R .…”

Section: Kaburagi: Effect Of Channel Asymmetry On the Glottal Flowmentioning

confidence: 99%

“…A similar computational fluid dynamics approach was used for both symmetrical and asymmetrical glottal channels [13,14]. On the other hand, it has been revealed that the analysis methods based on the boundary-layer approximation are highly accurate and computationally efficient [9][10][11]15]. Lagrée et al [16] applied a method called interactive boundary-layer (IBL) analysis to investigate the asymmetrical effects, and they calculated the distribution of the characteristic quantities of glottal flow along the channel.…”

Section: Introductionmentioning

confidence: 99%

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Effect of channel asymmetry on the behavior of flow passing through the glottis

Kaburagi

2012

Acoust. Sci. & Tech.

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A method for analyzing the behavior of flow passing through an asymmetrical glottal channel is presented. The method assumes the formation of a thin boundary layer near the glottal wall and an interaction between the boundary layer and the core flow. The core flow velocity is estimated in two dimensions employing a method of potential flow analysis, while the characteristic quantities of the boundary layer are determined by solving the integral momentum relation on the basis of the similarity of the velocity profiles within the layer. Estimation results for the volume flow rate, effective flow velocity, pressure distribution, driving force of the vocal folds, and flow separation point are presented for a total of 315 glottal configurations obtained by varying the angle of each vocal fold and the minimum glottal height. The results indicate that the boundary layer tends to reduce the effect of channel asymmetry, and the imbalance of the aerodynamic quantities between the two vocal folds is small unless the glottis widely opens and the angular difference of the vocal folds is considerable.

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“…An example of the application of these models is investigating the interaction between the voice-source system and the vocal-tract filter [6][7][8]. When producing speech, the transfer function of the vocal tract (and hence formants) is determined by the geometry (length and cross-sectional area) of the vocal tract.…”

Section: Introductionmentioning

confidence: 99%

A method for estimating vocal-tract shape from a target speech spectrum

Kaburagi

2015

Acoust. Sci. & Tech.

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We present a method to simultaneously estimate the cross-sectional area and length of the vocal tract from a speech spectrum. An iterative procedure determines the vocal-tract shape by gradually optimizing the parameter values to produce the target speech spectrum. The vocal-tract shape is updated in each iteration using a sensitivity function representing the change in formant frequency caused by a slight perturbation of the vocal-tract shape. Our method effectively optimizes the vocal-tract shape when combined with the perturbation relationship between the speech spectrum parameters (i.e., cepstral parameters) and formants. The estimation accuracy is examined using area function data for 10 English vowels (Story and Titze, J. Phon., 26, 223-260, 1998). The resulting average errors are 0.36 cm 2 for the cross-sectional area and 0.21 cm for the vocal-tract length. This corresponds to a 17.6% and 1.24% error, respectively. The formant frequency recovered from the estimated vocal-tract shape has an error of less than 4% for each of the first four formants. We also determine that the fundamental frequency of the target speech spectrum has an influence on the estimation accuracy.

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Voice production model integrating boundary-layer analysis of glottal flow and source-filter coupling

Cited by 9 publications

References 30 publications

A Simulation Study on the Effect of Glottal Boundary Conditions on Vocal Tract Formants

A Simulation Study on the Effect of Glottal Boundary Conditions on Vocal Tract Formants

Effect of channel asymmetry on the behavior of flow passing through the glottis

A method for estimating vocal-tract shape from a target speech spectrum

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