This chapter examines the conceptualization and measurement of contact phenomena in the context of bilingualism across various languages. The goal of the chapter is to account for various phonetic contact phenomena in sociolinguistic analysis, as well as providing context for elaborating on quantitative methodologies in sociophonetic contact linguistics. More specifically, the chapter provides a detailed account of global phenomena in modern natural speech contexts, as well as an up-to-date examination of quantitative methods in the field of sociolinguistics. The first section provides a background of theoretical concepts important to the understanding of sociophonetic contact in the formation of sound systems. The following sections focus on several key social factors that play a major part in the sociolinguistic approach to bilingual phonetics and phonology, including language dominance and age of acquisition at the segmental and the suprasegmental levels, as well as topics of language attitudes and perception, and typical quantitative methods used in sociolinguistics.

With close to 7,000 languages in use around the world today (Lewis, Simons, & Fennig, 2009) and only 195 countries (United Nations, 2018), being completely monolingual is quite rare as multilingualism is often the norm (Grin, 2004). Looking through the research literature, however, it would appear as though bilinguals are a unique population with distinct advantages or disadvantages from monolinguals. Spear (1984) proposed that what infants of all species learn and remember at any time in development is determined by the ecological challenges posed by their current environment and the survival value of responding successfully to them. Learning trajectories of monolingual and bilingual children are more similar than different, with differences reflecting the bilingual brain’s adaptations to the surrounding linguistic conditions. The rate and ease at which children learn language is surprising, as language acquisition is a very complex task, with infants having to quickly learn how to identify patterns within a continuous string of speech sounds (Saffran, Aslin, & Newport, 1996).