Chapter 1 introduces the pattern of /str/-retraction and then lays the theoretical groundworkfor the variationist approach to this sound change. The chapter first defines language variation and change and then provides an overview of research paradigms in interspeaker and intraspeaker variation. These approaches are completed with a section on meaning in language.

This chapter serves the purpose of introducing readers both to the paradigms and theoretical expectations in language change research as well as providing the foundation for the types and the nature of language-external variables that will later find their way into the methods and the statistical models developed.

Chapter 4 illustrates and discusses in detail the steps taken to evaluate the research questions. It first clarifies the methodological approach and then introduces the study design. The declared aim is to create a study that combines the larger number of tokens per speaker created by an experimental framework with the sample diversity and natural environment needed for sociolinguistic analyses. Further sections deal with the sample and the procedure. In this study, seventy-nine speakers with various gender, ethnicity, and age profiles were asked to complete naming tasks, a reading task, a re-narration and a free interview with a meta commentary section.

Chapter 5 describes the patterns found in the data set with a focus on /str/-clusters. Theanalysis starts with a general description of data dispersion and the nature of sibilants in the data set. It addresses the distribution of the data, showing that /str/-clusters are more likely to be retracted than pre-vocalic realizations of /s/. This section further establishes how the distance between /s/ and /ʃ/ can be described by center-of-gravity measurements. Following this operationalization, the focus is on internal factors of language change, namely the question of phonetic and lexical gradualness. Both types of gradualness are confirmed in the analysis of the sibilant space.

The following section focuses on a descriptive statistical account of further social factors in the description of /str/-lowering, of which ethnicity and age are the most relevant. Together with the linguistic factors, the final mixed-effects regression model is then developed and fully evaluated, indicating sibilant duration, age, and ethnicity as most important factors in the change. These results are further confirmed by a random forest regression.

In a qualitative extension of the insights gained through the regression analysis, a brief thematic analysis summarizes the patterns found in the commentary part of the interviews.

Chapter 3 is devoted to the origin, initiation, and modeling of sound change. It begins withtheories of why sound change exists and discusses the teleological and nonteleological approaches. It then connects various models of sound change to these initiation stages. The most pressing question in these models is whether they build on the notion of accumulation of errors, or the involvement of social context such that social interpretation lies at the heart of change initiation. From the micro perspective, the chapter then discusses how change propagates in the individual speaker or listener and how sound change may lead to phonologization as its final stage. It contrasts Neogrammarian sound change with lexical diffusion. It further connects exemplar theories and sound change by extending exemplar knowledge to social meaning. The chapter then addresses the state of the art in /str/-retraction research. It spans the entire linguistic attention to /str/-retraction, from Labov’s early fieldnotes, to Shapiro and Lawrence’s theoretical accounts, to later phonetic and sociolinguistic approaches. Based on the theoretical backdrop provided before and the state of the art in /str/-centered linguistic research, the research hypotheses of the study are then introduced.

Chapter 2 explains the phonetic and phonological background of sibilant analysis.It first establishes a definition of the phoneme and then continues to describe the sounds involved based on an articulatory point of view. These are then connected to acoustic theories of speech production that illustrate how prototypical articulatory gestures create the resulting sound waves that are perceived as phonemes. It specifically explains how source filter theory and turbulence are important to the production of sibilants. It then illustrates how the acoustic output created can be quantified and classified based on characteristics such as spectral mean, skewness, and kurtosis of the speech signal.

The chapter then moves on to suprasegmental theories and fundamentals of /str/-retraction research. It explains how exemplar models of the mental lexicon are suitable to describe the sound change at hand. It then briefly illustrates the uniqueness of triple-consonant clusters in English. As important processes in this sound change, coarticulation and assimilation are then differentiated.

Chapter 6 discusses both the phonological and the sociolinguistic findings of the study. It underlines that /str/-production is currently encroaching on the phonetic realization of post-alveolar sibilants for many speakers. Phonetically, there is no evidence for an effect of /t/, such that assimilation or coarticulation at a distance is likely. Lexical gradualness was found to be affected significantly be the age of speakers. The data further confirm phonetic gradualness as well as indicators of phonologization. The effect of duration in regression models serves as further evidence for coarticulation. From a sociolinguistic point of view, the chapter discusses the lack of a gender pattern and contrasts this with ethnicity. It further adresses the perception of /str/-clusters in the comments section, which support the assumption that /str/-retraction presents as change from below.

Chapter 7 presents the implications of the study on a larger scale. It argues that the study not only shows an interesting gender pattern such that not only females are the agents of change but, rather, everyone but White males are agents of the change. This has implications for the entire gender-in-language-change paradigm. It could mean that the gender patterns developed byLabov misrepresent how gender identification influences language change and that an entirely new model needs to be developed when more social complexity is included in studies of language change. It further addresses the need for larger, more diverse datasets and perception experiments to investigate the possibility of a local social meaning of this widespread variant.