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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 phenomena.
(ProQuest: ... denotes formulae omitted.)
he term quantal has often been applied to a subset of nonlinear effects in speech-traditionally those that underlie robust auditory-perceptual goals (e.g., Stevens, 1972, 1989; Stevens & Keyser, 2010). The present article uses computational biomechanical modeling to examine whether and to what extent different postures of the larynx exhibit quantal-like nonlinear behavior in biomechanical space. It is hoped that this examination of quantal biomechanics of the larynx will simultaneously (a) provide insight into the nature of speech motor control, particularly with respect to the larynx, and (b) aid in understanding the factors that shape the emergence and organization of speech sound systems more generally. Quantality and the closely related concept of saturation in biomechanics (see, e.g., Perkell, 2012) are terms that have been used to describe aspects of biomechanical robustness. In understanding the central role of quantal biomechanics in motor control and the emergence of speech sounds, it is necessary to consider the importance of biomechanical robustness in dimensionality reduction of motor systems.
The human vocal tract is endowed with seemingly innumerable degrees of freedom, raising the question of how a finite nervous system copes with the task of generating movement (e.g., Bernstein, 1967). A large and growing body of work in neurophysiology and other fields supports the long-standing notion that the human nervous system reduces dimensionality of these...