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We offer a dynamical model of phonological planning that provides a formal instantiation of how the speech production and perception systems interact during online processing. The model is developed on the basis of evidence from an experimental task that requires concurrent use of both systems, the so-called response-distractor task in which speakers hear distractor syllables while they are preparing to produce required responses. The model formalizes how ongoing response planning is affected by perception and accounts for a range of results reported across previous studies. It does so by explicitly addressing the setting of parameter values in representations. The key unit of the model is that of the dynamic field, a distribution of activation over the range of values associated with each representational parameter. The setting of parameter values takes place by the attainment of a stable distribution of activation over the entire field, stable in the sense that it persists even after the response cue in the above experiments has been removed. This and other properties of representations that have been taken as axiomatic in previous work are derived by the dynamics of the proposed model. (C) 2016 Elsevier Inc. All rights reserved.
We propose a theory of how the speech gesture determines change in a functionally relevant variable of vocal tract state (e.g., constriction degree). A core postulate of the theory is that the gesture determines how the variable evolves in time independent of any executive timekeeper. That is, the theory involves intrinsic timing of speech gestures. We compare the theory against others in which an executive timekeeper determines change in vocal tract state. Theories that employ an executive timekeeper have been proposed to correct for disparities between theoretically predicted and experimentally observed velocity profiles. Such theories of extrinsic timing make the gesture a nonautonomous dynamical system. For a nonautonomous dynamical system, the change in state depends not just on the state but also on time. We show that this nonautonomous extension makes surprisingly weak kinematic predictions both qualitatively and quantitatively. We propose instead that the gesture is a theoretically simpler nonlinear autonomous dynamical system. For the proposed nonlinear autonomous dynamical system, the change in state depends nonlinearly on the state and does not depend on time. This new theory provides formal expression to the notion of intrinsic timing. Furthermore, it predicts experimentally observed relations among kinematic variables.
We examined gestural coordination in C1C2 (C1 stop, C2 lateral or tap) word initial clusters using articulatory (electromagnetic articulometry) and acoustic data from six speakers of Standard Peninsular Spanish. We report on patterns of voice onset time (VOT), gestural plateau duration of C1, C2, and their overlap. For VOT, as expected, place of articulation is a major factor, with velars exhibiting longer VOTs than labials. Regarding C1 plateau duration, voice and place effects were found such that voiced consonants are significantly shorter than voiceless consonants, and velars show longer duration than labials. For C2 plateau duration, lateral duration was found to vary as a function of onset complexity (C vs. CC). As for overlap, unlike in French, where articulatory data for clusters have also been examined, clusters where both C1 and C2 are voiced show more overlap than where voicing differs. Further, overlap was affected by the C2 such that clusters where C2 is a tap show less overlap than clusters where C2 is a lateral. We discuss these results in the context of work aiming to uncover phonetic (e.g., articulatory or perceptual) and phonological forces (e.g., syllabic organization) on timing.
During a cue-distractor task, participants repeatedly produce syllables prompted by visual cues. Distractor syllables are presented to participants via headphones 150 ms after the visual cue (before any response). The task has been used to demonstrate perceptuomotor integration effects (perception effects on production): response times (RTs) speed up as the distractor shares more phonetic properties with the response. Here it is demonstrated that perceptuomotor integration is not limited to RTs. Voice Onset Times (VOTs) of the distractor syllables were systematically varied and their impact on responses was measured. Results demonstrate trial-specific convergence of response syllables to VOT values of distractor syllables.
In a preferential looking paradigm, we studied how children's looking behavior and pupillary response were modulated by the degree of phonological mismatch between the correct label of a target referent and its manipulated form. We manipulated degree of mismatch by introducing one or more featural changes to the target label. Both looking behavior and pupillary response were sensitive to degree of mismatch, corroborating previous studies that found differential responses in one or the other measure. Using time-course analyses, we present for the first time results demonstrating full separability among conditions (detecting difference not only between one vs. more, but also between two and three featural changes). Furthermore, the correct labels and small featural changes were associated with stable target preference, while large featural changes were associated with oscillating looking behavior, suggesting significant shifts in looking preference over time. These findings further support and extend the notion that early words are represented in great detail, containing subphonemic information.
Spectral change and duration as cues in Australian English listeners' front vowel categorization
(2018)
Australian English /iː/, /ɪ/, and /ɪə/ exhibit almost identical average first (F1) and second (F2) formant frequencies and differ in duration and vowel inherent spectral change (VISC). The cues of duration, F1 × F2 trajectory direction (TD) and trajectory length (TL) were assessed in listeners' categorization of /iː/ and /ɪə/ compared to /ɪ/. Duration was important for distinguishing both /iː/ and /ɪə/ from /ɪ/. TD and TL were important for categorizing /iː/ versus /ɪ/, whereas only TL was important for /ɪə/ versus /ɪ/. Finally, listeners' use of duration and VISC was not mutually affected for either vowel compared to /ɪ/.
Drawing on phonology research within the generative linguistics tradition, stochastic methods, and notions from complex systems, we develop a modelling paradigm linking phonological structure, expressed in terms of syllables, to speech movement data acquired with 3D electromagnetic articulography and X-ray microbeam methods. The essential variable in the models is syllable structure. When mapped to discrete coordination topologies, syllabic organization imposes systematic patterns of variability on the temporal dynamics of speech articulation. We simulated these dynamics under different syllabic parses and evaluated simulations against experimental data from Arabic and English, two languages claimed to parse similar strings of segments into different syllabic structures. Model simulations replicated several key experimental results, including the fallibility of past phonetic heuristics for syllable structure, and exposed the range of conditions under which such heuristics remain valid. More importantly, the modelling approach consistently diagnosed syllable structure proving resilient to multiple sources of variability in experimental data including measurement variability, speaker variability, and contextual variability. Prospects for extensions of our modelling paradigm to acoustic data are also discussed.
Previous studies suggest that there are special timing relations in syllable onsets. The consonants are assumed to be timed, on the one hand, with the vocalic nucleus and, on the other hand, with each other. These competing timing relations result in the C-center effect. However, the C-center effect has not consistently been found in languages with complex onsets. Moreover, it has occasionally been found in languages disallowing complex onsets. The present study investigates onset timing in German while discussing alternative explanations (not related to bonding) for the timing patterns observed. Six German speakers were recorded via Electromagnetic Articulography. The corpus contained items with four clusters (/sk/, /kv/, /gl/, and /pl/). The clusters occur in word-initial position, word-medial position, and across a word boundary preceding different vowels. The results suggest that segmental properties (i.e., oral-laryngeal coordination, coarticulatory resistance) determine the observed timing patterns, and specifically the absence or presence of the C-center effect.
We asked whether invariant phonetic indices for syllable structure can be identified in a language where word-initial consonant clusters, regardless of their sonority profile, are claimed to be parsed heterosyllabically. Four speakers of Moroccan Arabic were recorded, using Electromagnetic Articulography. Pursuing previous work, we employed temporal diagnostics for syllable structure, consisting of static correspondences between any given phonological organisation and its presumed phonetic indices. We show that such correspondences offer only a partial understanding of the relation between syllabic organisation and continuous indices of that organisation. We analyse the failure of the diagnostics and put forth a new approach in which different phonological organisations prescribe different ways in which phonetic indices change as phonetic parameters are scaled. The main finding is that invariance is found in these patterns of change, rather than in static correspondences between phonological constructs and fixed values for their phonetic indices.