Sociophonetics research is located at the interface of sociolinguistics and experimental phonetics. Its primary focus is to shed new light on the social-indexical phonetic properties of speech, revealing a wide range of phonetic parameters that map systematically to social factors relevant to speakers and listeners, and the fact that many of these involve particularly fine-grained control of both spatial and temporal dimensions of speech production. Recent methodological developments in acoustic and articulatory methods have yielded new insights into the nature of sociophonetic variation at the scale of entire speech communities as well as in respect of the detailed speech production patterns of individual speakers. The key theoretical dimension of sociophonetic research is to consider how models of speech production, processing, and acquisition should be informed by rapidly increasing knowledge of the ubiquity of social-indexical phonetic variation carried by the speech signal. In particular, this work is focused on inferring from the performance of speakers and listeners how social-indexical phonetic properties are interwoven into phonological representation alongside those properties associated with the transmission and interpretation of lexical-propositional information.