Juraj Simko

Emergent consonantal quantity contrast and context-dependence of gestural phasing

Abstract Embodied Task Dynamics is a modeling platform combining task dynamical implementation of articulatory phonology with an optimization approach based on adjustable trade-offs between production efficiency and perception efficacy. Within this platform we model a consonantal quantity contrast in bilabial stops as emerging from local adjustment of demands on relative prominence of the consonantal gesture conceptualized in terms of closure duration. The contrast is manifested in the form of two distinct, stable inter-gestural coordination patterns characterized by quantitative differences in relative phasing between the consonant and the coproduced vocalic gesture. Furthermore, the model generates a set of qualitative predictions regarding dependence of kinematic characteristics and inter-gestural coordination on consonant quantity and gestural context. To evaluate these predictions, we collected articulatory data for Finnish speakers uttering singletons and geminates in the same context as explored by the model. Statistical analysis of the data shows strong agreement with model predictions. This result provides support for the hypothesis that speech articulation is guided by efficiency principles that underlie many other types of embodied skilled action.

Emergence of prosodic boundary: Continuous effects of temporal affordance on inter-gestural timing

Abstract The bulk of our current knowledge about articulatory/acoustic signatures of prosodic structure comes from paradigms that elicit discrete prosodic variation intentionally produced by subjects. In this paper, we collect speech elicited through continuous variation in tempo and hypo–hyper articulation, and analyze spontaneous emergence of high-level prosodic boundaries as a means of resolving low-level tempo and precision demands. Our data show that as the area of structural affordance for a prosodic boundary comes under decreasing temporal pressure, the temporal coordination patterns of the gestures in the vicinity of this affordance get continuously rearranged. This re-arrangement is comprehensively captured with the optimization-based embodied task dynamics platform ( Simko and Cummins, 2010 , Simko and Cummins, 2011 ), in which this phenomenon can be modeled in terms of localized changes in relative demands on articulatory efficiency, perceptual clarity, and minimal duration, and the optimal resolution of these demands.

Quantity language speakers show enhanced subcortical processing

The complex auditory brainstem response (cABR) can reflect language-based plasticity in subcortical stages of auditory processing. It is sensitive to differences between language groups as well as stimulus properties, e.g. intensity or frequency. It is also sensitive to the synchronicity of the neural population stimulated by sound, which results in increased amplitude of wave V. Finnish is a full-fledged quantity language, in which word meaning is dependent upon duration of the vowels and consonants. Previous studies have shown that Finnish speakers have enhanced behavioural sound duration discrimination ability and larger cortical mismatch negativity (MMN) to duration change compared to German and French speakers. The next step is to find out whether these enhanced duration discrimination abilities of quantity language speakers originate at the brainstem level. Since German has a complementary quantity contrast which restricts the possible patterns of short and long vowels and consonants, the current experiment compared cABR between nonmusician Finnish and German native speakers using seven short complex stimuli. Finnish speakers had a larger cABR peak amplitude than German speakers, while the peak onset latency was only affected by stimulus intensity and spectral band. The results suggest that early cABR responses are better synchronised for Finns, which could underpin the enhanced duration sensitivity of quantity language speakers.

Connections of Grasping and Horizontal Hand Movements with Articulation in Czech Speakers

We have recently shown in Finnish speakers that articulation of certain vowels and consonants has a systematic influence on simultaneous grasp actions as well as on forward and backward hand movements. Here we studied whether these effects generalize to another language, namely Czech. We reasoned that if the results generalized to another language environment, it would suggest that the effects arise through other processes than language-dependent semantic associations. Rather, the effects would be likely to arise through language-independent interactions between processes that plan articulatory gestures and hand movements. Participants were presented with visual stimuli specifying articulations to be uttered (e.g., A or I), and they were required to produce a manual response concurrently with the articulation. In Experiment 1 they responded with a precision or a power grip, whereas in Experiment 2 they responded with a forward or a backward hand movement. The grip congruency effect was fully replicated: the consonant [k] and the vowel [α] were associated with power grip responses, while the consonant [t] and the vowel [i] were associated with precision grip responses. The forward/backward congruency effect was replicated with vowels [α], [o], which were associated with backward movement and with [i], which was associated with forward movement, but not with consonants [k] and [t]. These findings suggest that the congruency effects mostly reflect interaction between processes that plan articulatory gestures and hand movements with an exception that the forward/backward congruency effect might only work with vowel articulation.

Musical Sophistication and the Effect of Complexity on Auditory Discrimination in Finnish Speakers

Musical experiences and native language are both known to affect auditory processing. The present work aims to disentangle the influences of native language phonology and musicality on behavioral and subcortical sound feature processing in a population of musically diverse Finnish speakers as well as to investigate the specificity of enhancement from musical training. Finnish speakers are highly sensitive to duration cues since in Finnish, vowel and consonant duration determine word meaning. Using a correlational approach with a set of behavioral sound feature discrimination tasks, brainstem recordings, and a musical sophistication questionnaire, we find no evidence for an association between musical sophistication and more precise duration processing in Finnish speakers either in the auditory brainstem response or in behavioral tasks, but they do show an enhanced pitch discrimination compared to Finnish speakers with less musical experience and show greater duration modulation in a complex task. These results are consistent with a ceiling effect set for certain sound features which corresponds to the phonology of the native language, leaving an opportunity for music experience-based enhancement of sound features not explicitly encoded in the language (such as pitch, which is not explicitly encoded in Finnish). Finally, the pattern of duration modulation in more musically sophisticated Finnish speakers suggests integrated feature processing for greater efficiency in a real world musical situation. These results have implications for research into the specificity of plasticity in the auditory system as well as to the effects of interaction of specific language features with musical experiences.

Optimization-based modeling of speech timing

An optimization-based model of suprasegmental speech timing is presented.Timing patterns are modeled by trading off economy and clarity-related demands.Global and local weights allow for simulating different prosodic conditions.Simulation experiments demonstrate replication of various timing phenomena. We present a model of suprasegmental speech timing based on the assumption that speech patterns are shaped by global and local adjustments of trade-offs between conflicting demands of minimizing production effort and maximizing perceptual clarity. The model uses an optimization procedure to determine durations of suprasegmental constituents of simulated utterances by minimizing an independently motivated composite cost function. The cost is a function of the constituent durations and encompasses different components that represent independently derived measures of speaker-based production effort, listener-oriented perceptual clarity as well as time conceptualized as a resource shared between both parties, linked to transmission efficiency. The trade-offs between these influences can be globally and locally adjusted by weights assigned to individual cost components within the composite cost function. We show that this approach facilitates modeling a hierarchy of interacting prosodic features of utterances, such as different degrees of prominence or effects of speaking rate and overall requirements of clarity. We outline the theoretical foundations and the architecture of the model and present results of simulation experiments, demonstrating that the model correctly predicts a range of suprasegmental timing phenomena in stress-accent languages that have not been addressed by a unified model. Results underline the models capacity to account for several empirical observations regarding durational variation in speech.

The influence of fundamental frequency on perceived duration in spectrally comparable sounds

The perceived duration of a sound is affected by its fundamental frequency and intensity: higher sounds are judged to be longer, as are sounds with greater intensity. Since increasing intensity lengthens the perceived duration of the auditory object, and increasing the fundamental frequency increases the sound’s perceived loudness (up to ca. 3 kHz), frequency modulation of duration could be potentially explained by a confounding effect where the primary cause of the modulation would be variations in intensity. Here, a series of experiments are described that were designed to disentangle the contributions of fundamental frequency, intensity, and duration to perceived loudness and duration. In two forced-choice tasks, participants judged duration and intensity differences between two sounds varying simultaneously in intensity, fundamental frequency, fundamental frequency gliding range, and duration. The results suggest that fundamental frequency and intensity each have an impact on duration judgments, while frequency gliding range did not influence the present results. We also demonstrate that the modulation of perceived duration by sound fundamental frequency cannot be fully explained by the confounding relationship between frequency and intensity.