281 research outputs found

    Modeling the production of VCV sequences via the inversion of a biomechanical model of the tongue

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    A control model of the production of VCV sequences is presented, which consists in three main parts: a static forward model of the relations between motor commands and acoustic properties; the specification of targets in the perceptual space; a planning procedure based on optimization principles. Examples of simulations generated with this model illustrate how it can be used to assess theories and models of coarticulation in speech

    A biomechanical modeling study of the effects of the orbicularis oris muscle and jaw posture on lip shape

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    Purpose: The authors' general aim is to use biomechanical models of speech articulators to explore how possible variations in anatomical structure contribute to differences in articulatory strategies and phone systems across human populations. Specifically, they investigated 2 issues: (a) the link between lip muscle anatomy and variability in lip gestures and (b) the constraints of coupled lip/jaw biomechanics on jaw posture in labial sounds. Method: The authors used a model coupling the jaw, tongue, and face. First, the influence of the orbicularis oris (OO) anatomical implementation was analyzed by assessing how changes in depth (from epidermis to the skull) and peripheralness (proximity to the lip horn center) affected lip shaping. Second, the capability of the lip/jaw system to generate protrusion and rounding, or labial closure, was evaluated for different jaw heights. Results: Results showed that a peripheral and moderately deep OO implementation is most appropriate for protrusion and rounding; a superficial implementation facilitates closure; protrusion and rounding require a high jaw position; and closure is achievable for various jaw heights. Conclusions: Models provide objective information regarding possible links between anatomical and speech production variability across humans. Comparisons with experimental data will illustrate how motor control and cultural factors cope with these constraints

    Biomechanics of the orofacial motor system: Influence of speaker-specific characteristics on speech production

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    International audienceOrofacial biomechanics has been shown to influence the time signals of speech production and to impose constraints with which the central nervous system has to contend in order to achieve the goals of speech production. After a short explanation of the concept of biomechanics and its link with the variables usually measured in phonetics, two modeling studies are presented, which exemplify the influence of speaker-specific vocal tract morphology and muscle anatomy on speech production. First, speaker-specific 2D biomechanical models of the vocal tract were used that accounted for inter-speaker differences in head morphology. In particular, speakers have different main fiber orientations in the Styloglossus Muscle. Focusing on vowel /i/ it was shown that these differences induce speaker-specific susceptibility to changes in this muscle's activation. Second, the study by Stavness et al. (2013) is summarized. These authors investigated the role of a potential inter-speaker variability of the Orbicularis Oris Muscle implementation with a 3D biomechanical face model. A deeper implementation tends to reduce lip aperture; an increase in peripheralness tends to increase lip protrusion. With these studies, we illustrate the fact that speaker-specific orofacial biomechanics influences the patterns of articulatory and acoustic variability, and the emergence of speech control strategies

    The Distributed Lambda Model (DLM): A 3-D, Finite-Element Muscle Model Based on Feldman's Lambda Model; Assessment of Orofacial Gestures

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    International audiencePurpose: The authors aimed to design a distributed Lambda model (DLM), which is well-adapted to implement three-dimensional (3-D) Finite Element descriptions of muscles. Method: A muscle element model was designed. Its stress-strain relationships included the active force-length characteristics of the Lambda model along the muscle fibers, together with the passive properties of muscle tissues in the 3-D space. The muscle element was first assessed using simple geometrical representations of muscles in form of rectangular bars. Then, it was included in a 3-D face model, and its impact on lip protrusion was compared with the impact of a Hill-type muscle model. Results: The force-length characteristic associated with the muscle elements matched well with the invariant characteristics of the Lambda model. The impact of the passive properties was assessed. Isometric force variation and isotonic displacements were modeled. The comparison with a Hill-type model revealed strong similarities in terms of global stress and strain. Conclusion: The DLM accounted for the characteristics of the Lambda model. Biomechanically no clear differences were found between the DLM and a Hill-type model. Accurate evaluations of the Lambda model, based on the comparison between data and simulations, are now possible with 3-D biomechanical descriptions of the speech articulators because to the DLM

    Triangular body-cover model of the vocal folds with coordinated activation of the five intrinsic laryngeal muscles

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    Poor laryngeal muscle coordination that results in abnormal glottal posturing is believed to be a primary etiologic factor in common voice disorders such as non-phonotraumatic vocal hyperfunction. Abnormal activity of antagonistic laryngeal muscles is hypothesized to play a key role in the alteration of normal vocal fold biomechanics that results in the dysphonia associated with such disorders. Current low-order models of the vocal folds are unsatisfactory to test this hypothesis since they do not capture the co-contraction of antagonist laryngeal muscle pairs. To address this limitation, a self-sustained triangular body-cover model with full intrinsic muscle control is introduced. The proposed scheme shows good agreement with prior studies using finite element models, excised larynges, and clinical studies in sustained and time-varying vocal gestures. Simulations of vocal fold posturing obtained with distinct antagonistic muscle activation yield clear differences in kinematic, aerodynamic, and acoustic measures. The proposed tool is deemed sufficiently accurate and flexible for future comprehensive investigations of non-phonotraumatic vocal hyperfunction and other laryngeal motor control disorders.Fil: Alzamendi, Gabriel Alejandro. Universidad Nacional de Entre Ríos. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática; ArgentinaFil: Peterson, Sean D.. University of Waterloo; CanadáFil: Erath, Byron D.. Clarkson University; Estados UnidosFil: Hillman, Robert E.. Massachusetts General Hospital; Estados UnidosFil: Zañartu, Matías. Universidad Tecnica Federico Santa Maria.; Chil

    The quantal larynx: The stable regions of laryngeal biomechanics and implications for speech production

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    Purpose: Recent proposals suggest that (a) the high dimensionality of speech motor control may be reduced via modular neuromuscular organization that takes advantage of intrinsic biomechanical regions of stability and (b) computational modeling provides a means to study whether and how such modularization works. In this study, the focus is on the larynx, a structure that is fundamental to speech production because of its role in phonation and numerous articulatory functions. Method: A 3-dimensional model of the larynx was created using the ArtiSynth platform (http://www.artisynth.org). This model was used to simulate laryngeal articulatory states, including inspiration, glottal fricative, modal prephonation, plain glottal stop, vocal–ventricular stop, and aryepiglotto– epiglottal stop and fricative. Results: Speech-relevant laryngeal biomechanics is rich with “quantal” or highly stable regions within muscle activation space. Conclusions: Quantal laryngeal biomechanics complement a modular view of speech control and have implications for the articulatory–biomechanical grounding of numerous phonetic and phonological phenomen

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    A multilinear tongue model derived from speech related MRI data of the human vocal tract

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    We present a multilinear statistical model of the human tongue that captures anatomical and tongue pose related shape variations separately. The model is derived from 3D magnetic resonance imaging data of 11 speakers sustaining speech related vocal tract configurations. The extraction is performed by using a minimally supervised method that uses as basis an image segmentation approach and a template fitting technique. Furthermore, it uses image denoising to deal with possibly corrupt data, palate surface information reconstruction to handle palatal tongue contacts, and a bootstrap strategy to refine the obtained shapes. Our evaluation concludes that limiting the degrees of freedom for the anatomical and speech related variations to 5 and 4, respectively, produces a model that can reliably register unknown data while avoiding overfitting effects. Furthermore, we show that it can be used to generate a plausible tongue animation by tracking sparse motion capture data

    Statistical identification of articulatory roles in speech production.

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    The human speech apparatus is a rich source of information and offers many cues in the speech signal due to its biomechanical constraints and physiological interdependencies. Coarticulation, a direct consequence of these speech production factors, is one of the main problems affecting the performance of speech systems. Incorporation of production knowledge could potentially benefit speech recognisers and synthesisers. Hand coded rules and scores derived from the phonological knowledge used by production oriented models of speech are simple and incomplete representations of the complex speech production process. Statistical models built from measurements of speech articulation fail to identify the cause of constraints. There is a need for building explanatory yet descriptive models of articulation for understanding and modelling the effects of coarticulation. This thesis aims at providing compact descriptive models of realistic speech articulation by identifying and capturing the essential characteristics of human articulators using measurements from electro-magnetic articulography. The constraints on articulators during speech production are identified in the form of critical, dependent and redundant roles using entirely statistical and data-driven methods. The critical role captures the maximally constrained target driven behaviour of an articulator. The dependent role models the partial constraints due to physiological interdependencies. The redundant role reflects the unconstrained behaviour of an articulator which is maximally prone to coarticulation. Statistical target models are also obtained as the by-product of the identified roles. The algorithm for identification of articulatory roles (and estimation of respective model distributions) for each phone is presented and the results are critically evaluated. The identified data-driven constraints obtained are compared with the well known and commonly used constraints derived from the IPA (International Phonetic Alphabet). The identified critical roles were not only in agreement with the place and manner descriptions of each phone but also provided a phoneme to phone transformation by capturing language and speaker specific behaviour of articulators. The models trained from the identified constraints fitted better to the phone distributions (40% improvement) . The evaluation of the proposed search procedure with respect to an exhaustive search for identification of roles demonstrated that the proposed approach performs equally well for much less computational load. Articulation models built in the planning stage using sparse yet efficient articulatory representations using standard trajectory generation techniques showed some potential in modelling articulatory behaviour. Plenty of scope exists for further developing models of articulation from the proposed framework
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