The Time Course of Speech Perception and Production in Individual Language Users (NSF Grant BCS-1348150)

PI: Patrice Speeter Beddor
Co-PI: Andries W. Coetzee

The relation between speech production and perception is a foundational issue for theories of production and perception, and is similarly central to current approaches to the phonetics of sound change. This project explores the dynamics of perception in relation to the dynamics of production for the individual language user. The work is guided by the hypothesis that a language user’s perception and production repertoires or grammars are complexly related in ways that are mediated by wide-ranging (linguistic, social, psychological, and other) factors.

The focus of the project is coarticulation, that is, the overlapping articulatory movements necessary for fluent, comprehensible speech. Three studies were conducted, each of which addressed, for a targeted coarticulatory property, the following questions: (i) What is the time course of perception of coarticulated speech? (ii) What is the time course of the articulatory or aerodynamic consequences of the overlapping speech gestures? (iii) For the individual language user, what is the relation between (i) and (ii), that is, what is the relation between a listener’s dynamic use of coarticulatory information as the acoustic signal unfolds in real time and that language user’s own coarticulated productions?

Study 1: The time course of individuals’ perception of coarticulatory information is linked to their production: implications for sound change (Patrice Beddor, Andries Coetzee, Will Styler, Kevin McGowan, Julie Boland). Language 94(4), 2018.
Abstract: Understanding the relation between speech production and perception is foundational to phonetic theory, and is similarly central to theories of the phonetics of sound change. For sound changes that are arguably phonetically motivated, it is particularly important to establish that an individual listener’s selective attention—for example, to the redundant information afforded by coarticulation—is reflected in that individual’s own productions. This study reports the results of a pair of experiments designed to test the hypothesis that individuals who produce more consistent and extensive coarticulation will attend to that information especially closely in perception. The production experiment used nasal airflow to measure the time course of participants’ coarticulatory vowel nasalization; the perception experiment used an eye-tracking paradigm to measure the time course of those same participants’ attention to coarticulated nasality. Results showed that a speaker’s coarticulatory patterns predicted, to some degree, that individual’s perception, thereby supporting the hypothesis: participants who produced earlier onset of coarticulatory nasalization were, as listeners, more efficient users of nasality as that information unfolded over time. Thus, an individual’s perception of coarticulated speech is made public through their productions. 

Study 2: Producing and perceiving socially structured coarticulation: coarticulatory nasalization in Afrikaans (Andries Coetzee, Patrice Beddor, Will Styler, Stephen Tobin, Ian Bekker, Daan Wissing ). Laboratory Phonology 13(1), 2022.
Abstract: Most theories of phonetics assume a tight relation between production and perception, and recent years have also seen increasing evidence for such a relation at the level of the individual. For the most part, however, this evidence comes from socially homogeneous speech communities where the targeted pattern of variation is mostly socially neutral. What implications might socially structured phonetic variation in the speech community have for the perception-production link? If listeners can predict the phonetic patterns of a talker based on the talker’s actual or assumed identity, would they adjust their perceptual strategies accordingly, possibly weakening the link between their own production and perception patterns? This study reports the results of a pair of experiments that investigate the production and perception of coarticulatory vowel nasalization in Afrikaans, a language for which variation in coarticulatory nasalization is socially structured. Relying on nasal airflow measures, the production experiment showed that speakers of White Afrikaans produce more extensive coarticulatory nasalization than speakers of Kleurling Afrikaans. The perception experiment used an eye-tracking paradigm to assess listeners’ perceptual reliance on coarticulatory nasalization, and found (i) that Afrikaans speakers’ use of coarticulatory nasalization in production predicts their perceptual reliance on this information, (ii) that they rapidly adjust to the coarticulatory timing patterns in the speech of other speakers, but also (iii) that they do not adjust their perceptual reliance on coarticulation in response to the assumed identity of the speaker. The link between perception and production therefore persists, even in this situation of socially structured variation in coarticulatory timing. 

Study 3: Individuals’ perceptual retuning predicts articulatory accommodation: implications for sound change (Patrice Beddor, Andries Coetzee, Ian Calloway, Stephen Tobin).
Abstract: Individuals differ from each other, as speakers and listeners, in the extent to which they adapt to unfamiliar speech patterns. The hypothesis that listener-specific perceptual adjustments for an unfamiliar pattern are reflected in the listener-turned-speaker’s imitation of the pattern was tested for raising of English /æ/ before /g/ (e.g., [beɪg] bag but [bæk] back). For 37 American English participants, perceptual learning and spontaneous imitation of raised /æ(g)/ were assessed using eye-tracking and ultrasound imaging, respectively. Results support the hypothesis that perceptual retuning predicts, in part, articulatory accommodation: the more an individual perceptually adapted to raised /æ(g)/ (e.g., used [beɪg] to rapidly disambiguate backbag trials), the more that individual imitated raised /æ(g)/. These findings are viewed as relevant to the spread of (coarticulatorily motivated) change in that community members who attend particularly closely to innovative interlocutors’ novel forms may be especially likely to converge towards those forms in their subsequent productions.

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