Chapter 5 moves beyond regional accents to the importance of speech sound patterns for speakers’ presentations of their affiliations and for listeners’ interpretations of others.The chapter considers what sociophonetics offers the understanding of language and the social world and outlines some of the fundamental ways that the major social categories of social class, gender, ethnicity and age impact phonetic variation and change.Taking each of these topics in turn, the chapter unpacks how sociolinguistic studies of socially driven variation have established a foundation that underpins contemporary sociophonetic research and then transitions to survey sociophonetic research that investigates the influence of these four social factors on speech production.The chapter then turns to the role of these factors in speech processing, providing an overview of how factors such as class, gender and ethnicity have been shown to affect how listeners process variation in speech.The chapter closes with a discussion of how such research has contributed greatly to our understanding of how social factors correlate with linguistic factors.

Chapter 6 moves from the focus of Chapter 5 on macro level social categories to examine approaches to the study of within-individual variation and the construction of linguistic style and social identity.In particular, the chapter turns to what sociophonetic research, given its ability to examine gradient phonetic shifts, brings to this pursuit.The chapter begins by considering the study of individual variation in linguistics and phonetics more generally and then moves to discuss early approaches to sociolinguistic style and how those approaches evolved to present day interests in language and identity, style and interaction, within the realm of what is referred to as "third wave" research.Focusing in on such third wave approaches, the chapter then examines how sociophonetic studies on sibilant variation have provided an opportunity to explore both the social and cognitive aspects of socio-indexical variation.Finally, the chapter turns to what sociophonetic research, given its ability to hone in on very particular aspects of phonetic features, can bring to the study of linguistic performance, attending to studies that examine sibilant variation and speech perception.