This thesis seeks to better understand early phonological acquisition in a context in which linguistic input can be especially varied and variable. It focuses on preschoolers’ acquisition of Singapore English, a variety that emerged from long-term language contact, within a multilingual, multicultural setting that is linguistically and sociolinguistically complex. The four individual studies herein explore the variation in the English child-directed speech (CDS) of Singaporean caregivers and its possible connections with or effects on the outcomes of phonological acquisition in their preschool children.

The introductory chapter (Chapter 1) describes the sociolinguistic setting and reviews key factors that contribute to variable development and outcomes in early bilingual phonological acquisition, with a focus on input quality (i.e. specific phonetic or phonological properties of the input). Chapter 2 details the caregiver-child speech corpus that was developed for the production studies in this thesis.

The four studies in this thesis centre on two phonological features of Singapore English, namely the (non)release of coda oral stops and L-allophony. The first study (Chapter 3) reveals inter-adult variation in the release of English coda stops by ethnically Chinese caregivers, which is shown to be reflected in their children’s production. The other three studies focus on the realisations of coda /l/ in Singapore English, namely vocalised-l, dark-l and clear-l. Through a matched-guise test, Chapter 4 demonstrates that these three variants are imbued with diverse socio-indexical meanings, and their interpretation and evaluation are dependent on and shaped by the hearer’s individual experiences with the social world. Chapter 5 explores whether, how and why Malay caregivers vary their English coda /l/ in their CDS. The study reveals socially-conditioned variation between maternal and paternal CDS, and within maternal CDS. Finally, Chapter 6 examines the bilingual development of English and Malay laterals in Malay children, in order to understand how they negotiate the multiple allophones of /l/ in their caregivers’ input, and between the competing input models of their caregivers and significant others.

Chapter 7 reiterates and synthesises the findings, and at the same time, discusses six key implications that can be drawn from the four studies: (1) inter-speaker variation can be difficult to predict or model, (2) children acquire the differential speech properties in the input, (3) variation and/or inconsistencies in the input can affect the building of contrastive categories, (4) variation in the input can be complex, (5) there are multiple moderators of language outcomes, and (6) multiculturalism as a social force can be a moderator. The chapter then shows how usage-based accounts of language acquisition, specifically the exemplar model, may be useful in accounting for the variable outcomes observed in this thesis and in bilingual acquisition more generally. It concludes with some limitations and avenues for future work.