Assessing surface phonological specification through simulation and classification of phonetic trajectories

Abstract

Many previous studies have argued that phonology may leave some phonetic dimensions unspecified in surface representations. We introduce computational tools for assessing this possibility though simulation and classification of phonetic trajectories. The empirical material used to demonstrate the approach comes from electromagnetic articulography recordings of high-vowel devoicing in Japanese. Using Discrete Cosine Transform, tongue-dorsum movement trajectories are decomposed into a small number of frequency components (cosines differing in frequency and amplitude) that correspond to linguistically meaningful signal modulations, i.e. articulatory gestures. Stochastic generators of competing phonological hypotheses operate in this frequency space. Distributions over frequency components are used to simulate (i) the vowel-present trajectories and (ii) the vowel-absent trajectories. A Bayesian classifier trained on simulations assigns posterior probabilities to unseen data. Results indicate that /u/ is optionally produced without a vowel-height specification in Tokyo Japanese and that the frequency of such targetlessness varies systematically across phonological environments.

Research methods in articulatory phonetics I: Introduction and studying oral gestures

“…While spatial and temporal analyses of the kind presented above (displacement, lag or overlap) account for most of the research done using EMA, some recent works feature new analytical techniques. Among these are the Discrete Cosine Transform (DST) analysis, which captures dependencies between trajectory points (Shaw & Kawahara, ), the dynamic time warped (DTW) distance analyses comparing different speaking conditions (Meenakshi & Ghosh, Meenakshi & Ghosh, ), and correlation map analysis to examine articulatory coordination between two speakers (Vatikiotis‐Bateson, Barbosa, & Best, ).…”

Limits on gestural reorganization following vowel deletion: The case of Tokyo Japanese

“…2 There is some debate on whether /u/ in Japanese is generally rounded or not (see Vance, 2008), with some authors preferring to characterize the high back vowel as /ɯ/ (unrounded). The sensors on the upper and lower lip in Shaw & Kawahara (2018a) did not provide clear evidence for rounding on voiced /u/. See their supplementary materials for kinematic trajectories of the lips.…”

“…The data that we are working with has already been classified for vowel presence/absense on the basis of the tongue dorsum trajectory, results reported in Shaw & Kawahara (2021) (for method, see also Shaw & Kawahara, 2018a). For completeness, we briefly summarize the method here.…”

A dynamic neural field model of leaky prosody: proof of concept

“…For example, Roon and Gafos (2016) and Harper (2021) develop DFT models of the millisecond timescale of single consonant production while Gafos and Kirov (2010) capture gradual shift in phonological representations at the longer timescale (see also Tilsen, 2019). Modelling speech production as a cognitive process that unfolds in time distinguishes DFT from stochastic generative models (e.g., Shaw & Gafos, 2015;Shaw & Kawahara, 2018), Exemplar Theories (e.g., Pierrehumbert, 2001), and agent-based models (e.g., Harrington & Schiel, 2017), which treat speech production as a timeless process of statistical sampling. For the purposes of the simulations reported on here, 𝜏 is held constant, at 20.…”