The effect of glottal opening on the acoustic response of the vocal tract (original) (raw)
Related papers
A Simulation Study on the Effect of Glottal Boundary Conditions on Vocal Tract Formants
Interspeech 2017, 2017
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.
Effects of a vocal-tract constriction on the glottal source: experimental and modelling studies
Journal of Phonetics, 1986
The effects of a vocal-tract constriction on the glottal source were examined, based on acoustic and electroglottographic (EGG) data. Six subjects phonated through an apparatus in which constrictions of various sizes were alternated with a relatively unconstricted configuration. Measurements of glottal open time were made from the EGG data, and the effect of the constriction on glottal pulse shape was inferred from the spectrum of the acoustic signal. The data show a longer open time for the more constricted configurations, as well as a decreased pulse area, less abrupt closing slope of the pulse, and wider bandwidth of the first formant. Variability in all of the measures was apparent across subjects. We also examined the behavior of a two-mass model of the vocal folds which it is coupled to vocal-tract configurations with various degrees of constriction. There was general agreement between the glottal pulse waveforms generated by the model and those inferred from the speech experiments.
The Journal of the Acoustical Society of America, 2013
Even though incomplete glottal closure is present in normal and pathological voices, it has received little attention in self-sustained models of phonation. The effects of acoustic interaction due to a posterior glottal gap on the tissue dynamics, energy transfer, and glottal aerodynamics were numerically investigated. The domain was prescribed as flow through two separate orifices (posterior gap and membranous vocal folds) that merge in the supraglottal tract, with the governing flow equations determined from a control volume analysis based on conservation of mass and linear momentum. The equations of motion remained unaffected, although the driving forces were indirectly altered through the acoustic interaction. The method was implemented using the body-cover model, wave-reflection-analog sound propagation, and a boundarylayer asymmetric flow solver. The inclusion of a gap area of 0.05 cm2 reduced the RMS energy transfer from the fluid to the vocal folds by more than 35% and radiated SPL by 9 dB. When compensating for this reduction with an increased subglottal pressure to match the SPL, a significant increase in MFDR and AC flow was noted, thus mimicking vocal hyperfunction. In addition, posterior gap areas yielded a glottal airflow more proportional to the incident transglottal pressure drop than the glottal area.
Model of acoustic interaction between the vocal tract, subglottal region, and vocal source
Journal of Communications Technology and Electronics, 2010
This study is devoted to constructing a mathematical model of acoustic interaction between the glottal volume velocity, vocal tract, and subglottal region (trachea, bronchi, and lungs). The model is based on the approximation of the acoustic impedances by autoregressive models with a moving mean. The exper imental results are in good agreement with the data of other studies on interaction of the vocal source and vocal tract.
Journal of Sound and Vibration, 2016
Phonation into tubes is used for voice training and therapy. In the present study, the formant frequencies were estimated from measurements of the acoustic pressure and the acoustic input impedance for a plexiglass model of the vocal tract (VT) prolonged by a glass tube. Similar transfer function measurements were performed with a human VT in vivo. The experimental results matched the mathematical modelling and confirmed the legitimacy of assuming rigid walls in mathematical simulations of the acoustic characteristics of an artificial VT model prolonged by a tube. However, this study also proved a considerable influence from soft tissues in the yielding walls of human VT cavities on the first formant frequency, F1. The measured F1 for the VT model corresponded to the computed value of 78 Hz. The experiments in a human instead resulted in a much higher value of F1: about 200 Hz. The results confirm that a VT model with yielding walls must be considered for mathematical modelling of the occluded or semi-occluded human vocal tract, e.g. prolonged by tubes or straws. This is explained by an acoustic-structural interaction of the vocal tract cavities with a mechanical low-frequency resonance of the soft tissue in the larynx.
Glottal flow waveforms estimated by inverse filtering acoustic speech pressure signals were compared to glottal area functions obtained by digital high-speed imaging of the vocal fold vibration. Speech data consisted of breathy, normal and pressed phonations produced by two male and one female subjects. The results yield both qualitative and quantitative information about the relationship between the glottal flow and the corresponding area function. It was shown, for example, that a distinct knee in the glottal flow waveform in the opening phase corresponds to the abrupt opening of the vocal folds in normal and pressed phonation. In addition, the obtained quantitative data corroborates known theoretical considerations according to which the shape of the glottal flow is more asymmetric than the corresponding area function.
Canadian Acoustics, 2009
The purpose of this work, is to describe the effects of the coupling of the subglottic and supra glottic cavities of the human phonatory apparatus. For this, we will determine and use the transfer function of the vocal tract evaluated owing to an exploration of the human phonatory system using an external excitation using a pseudo random sequence; this method was developed by Djeradi et. al. 1991. This evaluation will be carried out on the basis of the following three conditions of the glottis: open glottis, closed glottis and variable glottis. One of the advantages of this method will be used, indeed, it is possible, at the time of the same expiry phase that corresponding to a sustained articulatory configuration, to record the signal of the sound itself and the useful signal for the measurement of the transfer function. The comparison of the various spectral data thus obtained highlights the subglottic effects of coupling on the one hand and shows that the conditions at the glottis have an influence on the resonances of the supraglottic cavities on the other hand. This enabled us highlight an increase in the value of the resonance frequencies, of the band-widths and a modification of the deviation between the resonances of the vocal tract. We have also noted the appearance of additional resonances peaks that can correspond to subglottic cavities During the second phase, we reproduced these effects by simulations on geometrical configurations obtained by the X-rays method performed on the same person and for the same configurations. s o m m a i r e Dans ce travail, nous allons décrire les effets de couplage des parties subglottiques et supra glottiques de l'appareil phonatoire humain. Pour cela, nous allons déterminer et exploiter la fonction de transfert du conduit vocal évaluée grâce à une exploration du système phonatoire humain à l 'aide d 'une excitation extérieure par une séquence pseudo aléatoire, cette méthode a été développée par Djeradi & al en 1991. Cette évaluation sera faite pour les 3 conditions de la glotte : glotte ouverte, glotte fermée et glotte variable. Nous allons utiliser l'un des avantages de cette méthode, en effet, il est possible, lors de la même phase d 'expiration correspondant à une configuration articulatoire soutenue, d 'enregistrer le signal du son lui-même et le signal utile pour la mesure de la fonction de transfert. La comparaison des différentes données spectrales ainsi obtenues permet la mise en évidence des effets de couplage subglottiques d 'une part et montre que les conditions à la glotte ont une influence sur les résonances des cavités supraglottiques d 'autre part. C 'est ainsi que nous avons pu mettre en évidence un accroissement de valeur des fréquences de résonance, des bandes passantes et une modification de l'écart entre les résonances du conduit vocal. Nous avons également noté l'apparition de pics de résonances supplémentaires pouvant correspondre à des formants subglottiques. Dans une seconde phase, nous avons reproduit ces effets par des simulations sur des configurations géométriques obtenues par la méthode des rayons X sur le même sujet et pour les mêmes configurations.
Effect of the Signal Measured from the Glottis on Determination of the Vocal Tract Shape
Annals of Biomedical Engineering, 2000
All-pole and pole-zero models for the vocal tract are developed. First an impulse train, then the pressure signal measured from the glottis, is used as the input in the models. The models for eight Turkish vowels produced by one male subject are studied to determine the effects of the presumed impulse train and the pressure signal measured from the glottis on the estimation of the vocal tract shape. The motion of the tongue is also examined for a whole word. © 1998 Biomedical Engineering Society. ͓S0090-6964͑98͒01006-6͔
Influence of glottal cross-section shape on phonation onset
The Journal of the Acoustical Society of America, 2014
Phonation models commonly rely on the assumption of a two-dimensional glottal geometry to assess kinetic and viscous flow losses. In this paper, the glottal cross-section shape is taken into account in the flow model in order to capture its influence on vocal folds oscillation. For the assessed cross-section shapes (rectangular, elliptical, or circular segment) the minimum pressure threshold enabling to sustain vocal folds oscillation is altered for constriction degrees smaller than 75%. The discrepancy between cross-section shapes increases as the constriction degree decreases.