Associating the origin and spread of sound change using agent-based modelling applied to /s/-retraction in English

Abstract

The study explored whether an asymmetric phonetic overlap between speech sounds could be turned into sound change through propagation around a community of speakers. The focus was on the change of /s/ to /ʃ/ which is known to be more likely than a change in the other direction both synchronically and diachronically. An agent-based model was used to test the prediction that communication between agents would advance /s/-retraction in /str/ clusters (e.g. string). There was one agent per speaker and the probabilistic mapping between words, phonological classes, and speech signals could be updated during communication depending on whether an agent listener absorbed an incoming speech signal from an agent talker into memory. Following interaction, sibilants in /str/ clusters were less likely to share a phonological class with prevocalic /s/ and were acoustically closer to /ʃ/. The findings lend support to the idea that sound change is the outcome of a fortuitous combination of the relative size and orientation of phonetic distributions, their association to phonological classes, and how these types of information vary between speakers that happen to interact with each other.

Sound change and coarticulatory variability involving English /ɹ/

“…The most well-studied /ɹ/-conditioned sound change is the retraction of /s/ in /stɹ/ clusters (e.g., street pronounced as [ʃtɹit]). It is unclear what the primary initiating factor of /str/ retraction was, but it is either directly or indirectly triggered by the following /ɹ/, and appears as a pronunciation variant in many English-speaking communities, such as Pennsylvania (Labov 1984;Gylfadottir 2015), Georgia (Phillips 2001), Louisiana ( Rutter 2011), North Carolina (Piergallini 2011;Wilbanks 2017), Oklahoma (Rutter 2014), Newfoundland (Clarke 2008), the UK (Altendorf 2003;Bass 2009;Glain 2014), New Zealand (Lawrence 2000;Bauer & Warren 2008;Gordon & Maclagan 2008), and Australia (Stevens & Harrington 2016;Stevens et al 2019). Two different mechanisms underlying /stɹ/ retraction have been postulated.…”

“…4 Previous research such as Baker et al (2011) leads us to expect patterns like /stɹ/ retraction and /tɹ/ and /dɹ/ affrication to be instances of phonological assimilation for most talkers, and thus be less sensitive to the phonetic details of the local triggering /ɹ/ than during the initial stages of these changes. In other words, these talkers have performed the reclassification of /s/ before /tɹ/ into the /ʃ/ category, as modeled by Stevens et al (2019). While /ɹ/ may continue to exert some influence on the preceding sound, it is not the same process as that which conditioned the initial change, especially if the target sound is now phonologically distinct.…”

What is learned from exposure: an error-driven approach to productivity in language

“…Our study thus shows that there may be systematicity at a different level than typically considered by linguists, and that naïve language users are sensitive to patterns at this particular level (see also Stevens, Harrington, & Schiel, 2019) even though there is no clear form-function relationship.…”

Contextualizing /s/ retraction: Sibilant variation and change in Washington D.C. African American Language

“…Although there are many remaining questions to ask about the nature of this relationship, this observation has implications for our understanding of the sound change. For example, Stevens et al (2019:11) suggested that an individual's split of /stɹ/ from /s/ (e.g., an intermediate /stɹ/ form), or merger of /stɹ/ with /ʃ/, is more likely to occur if speakers have more proximal /s/-/ʃ/ in acoustic space (as is the case for our working-class speakers). Therefore, the distributions of the rest of the sibilant space are relevant for examinations of /stɹ/ retraction across communities and social groups within communities.…”

“…Beyond this work, however, it is unclear whether a paucity of research on =ʃ= variation is because speakers do not make as much use of it for socioindexical meaning, because it is relatively stable over time, or, more simply, because of an omission on the part of researchers to fully investigate these issues. For example, the sound-change literature observes that change in voiceless sibilants is asymmetrical such that =s= retracts to(ward) =ʃ=, but that =ʃ= does not appear to front to(ward) =s= (Stevens, Harrington, & Schiel, 2019). There are no claims in sociolinguistics that =ʃ= is used for the same type of identity work as =s=, though of course this may be due simply to the absence of research examining =ʃ= variation in the first place.…”