Sociophonetics is one of the sub-branches of the discipline that has attracted a great deal of attention over the last decade. Recent advances in speech science and their technological simulations allow increasingly sophisticated studies of the progress of language contact and change. These studies, particularly those at the level of pronunciation, show that language variety is robust and socially embedded in interesting ways. Instrumental studies of language variety contact and change have focused on the role of social categories and attitudes in variety perception as well as production. Some of the studies presented in this volume look at the specific role of social factors in the formation, progress, and deterrence of intralingual contact and change; while others look at the ways in which social identities and beliefs influence a listener's ability to identify and comprehend varieties. These studies use detailed acoustic analyses of production speech data and of responses to samples of data based on such analyses. Although the book assumes some knowledge of basic acoustics and variationist studies, the general introduction plus chapter and section introductions provide a review of practices in the field, including those of collection, analysis, and interpretation.