The term sociophonetics refers to the interface of sociolinguistics and phonetics, and specifically to the use of modern phonetic methods in the quantitative analysis of language variation and change. Although its definition can be quite broad, including any sociolinguistic study involving sounds analysed impressionistically, it usually implies the use of instrumental techniques. This chapter takes the view of sociophonetics as a tool contributing to the understanding of the nature of language variation and change. Assuming a basic knowledge of acoustic phonetics, it focuses on sociophonetic methodology, particularly in the practice of acoustic vowel analysis.