Comparing Two Smoothing Approaches in Estimating Kinematic Parameters.

Purpose: We compare two signal smoothing and differentiation approaches: a frequently used approach in the speech community of digital filtering with approximation of derivatives by finite differences and a spline smoothing approach widely used in other fields of human movement science.

Method: In particular, we compare the values of a classic set of kinematic parameters estimated by the two smoothing approaches and assess, via regressions, how well these reconstructed values conform to known laws about relations between the parameters.

Results: Substantially smaller regression errors were observed for the spline smoothing than for the filtering approach.

How thresholding in segmentation affects the regression performance of the linear model.

Evaluating any model underlying the control of speech requires segmenting the continuous flow of speech effectors into sequences of movements. A virtually universal practice in this segmentation is to use a velocity-based threshold which identifies a movement onset or offset as the time at which the velocity of the relevant effector breaches some threshold percentage of the maximal velocity. Depending on the threshold choice, more or less of the movement's trajectory is left in for model regression.

Spatiotemporal coordination in word-medial stop-lateral and s-stop clusters of American English.

This paper is concerned with the relation between syllabic organization and intersegmental spatiotemporal coordination using Electromagnetic Articulometry recordings from seven speakers of American English (henceforth, English). Whereas previous work on English has focused on word-initial clusters (preceding a vowel whose identity was not systematically varied), the present work examined word-medial clusters /pl, kl, sp, sk/ in the context of three different vowel heights (high, mid, low). Our results provide evidence for a global organization for the segments involved in these cluster-vowel combinations.

Respect the surroundings: Effects of phonetic context variability on infants' learning of minimal pairs.

Fourteen-month-olds' ability to distinguish a just learned word, /buːk/, from its minimally different word, /duːk/, was assessed under two pre-exposure conditions: one where /b, d/-initial forms occurred in a varying vowel context and another where the vowel was fixed but the final consonant varied. Infants in the experiments benefited from the variable vowel but not from the variable final consonant context, suggesting that vowel variability but not all kinds of variability are beneficial. These results are discussed in the context of time-honored observations on the vowel-dependent nature of place of articulation cues for consonants.

Perceptuomotor compatibility effects in vowels: Effects of consonantal context and acoustic proximity of response and distractor.

In a cue-distractor task, speakers' response times (RTs) were found to speed up when they perceived a distractor syllable whose vowel was identical to the vowel in the syllable they were preparing to utter. At a more fine-grained level, subphonemic congruency between response and distractor-defined by higher number of shared phonological features or higher acoustic proximity-was also found to be predictive of RT modulations. Furthermore, the findings indicate that perception of vowel stimuli embedded in syllables gives rise to robust and more consistent perceptuomotor compatibility effects (compared to isolated vowels) across different response-distractor vowel pairs.

Perceptuomotor compatibility effects in vowels: Beyond phonemic identity.

Perceptuomotor compatibility between phonemically identical spoken and perceived syllables has been found to speed up response times (RTs) in speech production tasks. However, research on compatibility effects between perceived and produced stimuli at the subphonemic level is limited. Using a cue-distractor task, we investigated the effects of phonemic and subphonemic congruency in pairs of vowels.

Only the right noise? Effects of phonetic and visual input variability on 14-month-olds' minimal pair word learning.

Seminal work by Werker and colleagues (Stager & Werker [1997] Nature, 388, 381-382) has found that 14-month-old infants do not show evidence for learning minimal pairs in the habituation-switch paradigm. However, when multiple speakers produce the minimal pair in acoustically variable ways, infants' performance improves in comparison to a single speaker condition (Rost & McMurray [2009] Developmental Science, 12, 339-349). The current study further extends these results and assesses how different kinds of input variability affect 14-month-olds' minimal pair learning in the habituation-switch paradigm testing German learning infants.

Fitts' Law in Tongue Movements of Repetitive Speech.

Fitts' law, perhaps the most celebrated law of human motor control, expresses a relation between the kinematic property of speed and the non-kinematic, task-specific property of accuracy. We aimed to assess whether speech movements obey this law using a metronome-driven speech elicitation paradigm with a systematic speech rate control. Specifically, using the paradigm of repetitive speech, we recorded via electromagnetic articulometry speech movement data in sequences of the form /CV…/ from 6 adult speakers.

Temporal Aspects of Word Initial Single Consonants and Consonants in Clusters in Spanish.

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.

The speed-curvature power law in tongue movements of repetitive speech.

The speed-curvature power law is a celebrated law of motor control expressing a relation between the kinematic property of speed and the geometric property of curvature. We aimed to assess whether speech movements obey this law just as movements from other domains do. We describe a metronome-driven speech elicitation paradigm designed to cover a wide range of speeds.

Immediate phonetic convergence in a cue-distractor paradigm.

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.

Spectral change and duration as cues in Australian English listeners' front vowel categorization.

Australian English /iː/, /ɪ/, and /ɪə/ exhibit almost identical average first (1) and second (2) formant frequencies and differ in duration and vowel inherent spectral change (VISC). The cues of duration, 1 × 2 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/.

Children's gradient sensitivity to phonological mismatch: considering the dynamics of looking behavior and pupil dilation.

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.

Pupillometry registers toddlers' sensitivity to degrees of mispronunciation.

This study introduces a method ideally suited for investigating toddlers' ability to detect mispronunciations in lexical representations: pupillometry. Previous research has established that the magnitude of pupil dilation reflects differing levels of cognitive effort. Building on those findings, we use pupil dilation to study the level of detail encoded in lexical representations with 30-month-old children whose lexicons allow for a featurally balanced stimulus set.

Perceiving while producing: Modeling the dynamics of phonological planning.

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.

Stochastic time models of syllable structure.

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.

Perceptuo-motor effects of response-distractor compatibility in speech: beyond phonemic identity.

Previous studies have found faster response times in a production task when a speaker perceives a distractor syllable that is identical to the syllable they are required to produce. No study has found such effects when a response and a distractor are not identical but share parameters below the level of the phoneme. Results from Experiment 1 show some evidence of a response-time effect of response-distractor voicing congruency.

Articulatory characteristics of Hungarian 'transparent' vowels.

Using a combination of magnetometry and ultrasound, we examined the articulatory characteristics of the so-called 'transparent' vowels [i], [i], and [e] in Hungarian vowel harmony. Phonologically, transparent vowels are front, but they can be followed by either front or back suffixes. However, a finer look reveals an underlying phonetic coherence in two respects.

Dynamics of phonological cognition.

A fundamental problem in spoken language is the duality between the continuous aspects of phonetic performance and the discrete aspects of phonological competence. We study 2 instances of this problem from the phenomenon of voicing neutralization and vowel harmony. In each case, we present a model where the experimentally observed continuous distinctions are linked to the discreteness of phonological form using the mathematics of nonlinear dynamics.

The scope of linguistic generalizations: evidence from Hebrew word formation.

Does the productive use of language stem from the manipulation of mental variables (e.g. "noun", "any consonant")? If linguistic constraints appeal to variables, rather than instances (e.