387 research outputs found
A 3D biomechanical vocal tract model to study speech production control: How to take into account the gravity?
This paper presents a modeling study of the way speech motor control can deal
with gravity to achieve steady-state tongue positions. It is based on
simulations carried out with the 3D biomechanical tongue model developed at
ICP, which is now controlled with the Lambda model (Equilibrium-Point
Hypothesis). The influence of short-delay orosensory feedback on posture
stability is assessed by testing different muscle force/muscle length
relationships (Invariant Characteristics). Muscle activation patterns necessary
to maintain the tongue in a schwa position are proposed, and the relations of
head position, tongue shape and muscle activations are analyzed
Influences of tongue biomechanics on speech movements during the production of velar stop consonants: a modeling study
This study explores the following hypothesis: forward looping movements of
the tongue that are observed in VCV sequences are due partly to the anatomical
arrangement of the tongue muscles and how they are used to produce a velar
closure. The study uses an anatomically based 2D biomechanical tongue model.
Tissue elastic properties are accounted for in finite-element modeling, and
movement is controlled by constant-rate control parameter shifts. Tongue
raising and lowering movements are produced by the model with the combined
actions of the genioglossus, styloglossus and hyoglossus. Simulations of V1CV2
movements were made, where C is a velar consonant and V is [a], [i] or [u]. If
V1 is one of the vowels [a] and [u], the resulting trajectories describe
movements that begin to loop forward before consonant closure and continue to
slide along the palate during the closure. This prediction is in agreement with
classical data published in the literature. If V1 is vowel [i], we observe a
small backward movement. This is also in agreement with some measurements on
human speakers, but it is also in contradiction with the original data
published by Houde (1967). These observations support the idea that the
biomechanical properties of the tongue could be the main factor responsible for
the forward loops when V1 is a back vowel. In the left [i] context, it seems
that additional factors have to be taken into considerations, in order to
explain the observations made on some speaker
Biomechanics of the orofacial motor system: Influence of speaker-specific characteristics on speech production
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
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
The influence of the palate shape on articulatory token-to-token variability
Articulatory token-to-token variability not only depends on linguistic aspects like the phoneme inventory of a given language but also on speaker specific morphological and motor constraints. As has been noted previously (Perkell (1997), Mooshammer et al. (2004)) , speakers with coronally high "domeshaped" palates exhibit more articulatory variability than speakers with coronally low "flat" palates. One explanation for that is based on perception oriented control by the speaker. The influence of articulatory variation on the cross sectional area and consequently on the acoustics should be greater for flat palates than for domeshaped ones. This should force speakers with flat palates to place their tongue very precisely whereas speakers with domeshaped palates might tolerate a greater variability. A second explanation could be a greater amount of lateral linguo-palatal contact for flat palates holding the tongue in position. In this study both hypotheses were tested
A biomechanical modeling study of the effects of the orbicularis oris muscle and jaw posture on lip shape
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
Supralaryngeal control in Korean velar stops
International audienceThe aim of this study was to investigate the supralaryngeal control of the production of the Korean three-way contrast in velar stops. First, an EMA-experiment with three Korean speakers was carried out, and the kinematic properties of the tongue back were analyzed (length of the deceleration phase of the movement, peak velocity, peak acceleration, amplitude and duration of the looping movement during consonantal closure, and angle of incidence between tongue and palate at contact onset). To understand the potential motor control mechanisms underlying the production of the three-way contrast, the target hypothesis which suggests that articulator movements in stops are directed towards a target at or beyond the palate, was evaluated by comparing its predictions with our experimental findings. Evidence was found in support of this hypothesis. Hence, the hypothesis was further explored in a modeling study. The results suggest that variability in the articulatory parameters can be explained by a single control parameter, namely the target position of the tongue. In a third step the Korean velar stops were simulated by varying the target position. The results show that the main trends of the simulated consonants are in good agreement with the experimental findings
Origins of vocal-entangled gesture
Gestures during speaking are typically understood in a representational framework: they represent absent or distal states of affairs by means of pointing, resemblance, or symbolic replacement. However, humans also gesture along with the rhythm of speaking, which is amenable to a non-representational perspective. Such a perspective centers on the phenomenon of vocal-entangled gestures and builds on evidence showing that when an upper limb with a certain mass decelerates/accelerates sufficiently, it yields impulses on the body that cascade in various ways into the respiratory–vocal system. It entails a physical entanglement between body motions, respiration, and vocal activities. It is shown that vocal-entangled gestures are realized in infant vocal–motor babbling before any representational use of gesture develops. Similarly, an overview is given of vocal-entangled processes in non-human animals. They can frequently be found in rats, bats, birds, and a range of other species that developed even earlier in the phylogenetic tree. Thus, the origins of human gesture lie in biomechanics, emerging early in ontogeny and running deep in phylogeny
Individual Differences in Speech Production and Perception
Inter-individual variation in speech is a topic of increasing interest both in human sciences and speech technology. It can yield important insights into biological, cognitive, communicative, and social aspects of language. Written by specialists in psycholinguistics, phonetics, speech development, speech perception and speech technology, this volume presents experimental and modeling studies that provide the reader with a deep understanding of interspeaker variability and its role in speech processing, speech development, and interspeaker interactions. It discusses how theoretical models take into account individual behavior, explains why interspeaker variability enriches speech communication, and summarizes the limitations of the use of speaker information in forensics
- …