Researchers in bilingualism seek to identify factors that are associated with specific features of bilingual speech. One such predictive factor is language dominance, typically understood as the degree to which one of the languages of a bilingual is more often and more proficiently used. In this chapter we review landmark studies that demonstrate the power of language dominance in predicting fine-grained phonetic and phonological characteristics of speech production and on the perceptual and processing abilities in one or both languages of bilinguals. We then critically examine the construct of dominance and identify ways that dominance can be and has been measured, as well as challenges inherent in the measurement of dominance. We follow demonstrating the dynamic character of dominance by reviewing research on dominance switches and shifts. This is followed by a review of extant studies on language dominance in bilingual speech production, perception, and processing in both languages. We conclude with four areas where research can be fruitfully directed.

This chapter discusses the Ontogeny Phylogeny Model (OPM), which focuses on the formation and development of second language phonological systems. It proposes an interrelationship between L2 native-like productions, L1 transfer, and universal factors. The model argues that chronologically, and as style becomes increasingly formal, L2 native-like processes increase, L1 transfer processes decrease, and universal processes increase and then decrease. It further claims that the roles of universals and L1 transfer are mediated by markedness and similarity, both of which slow L2 acquisition. Specifically, in similar phenomena L1 transfer processes persist, while in marked phenomena universal processes persist. The OPM also argues that these same principles obtain for learners acquiring more than one L2, monolingual and bilingual acquisition, and L1 attrition. In addition to the chronological stages and variation of the individual learner, the model claims that these relationships hold true for language variation and change, including pidgins and creoles.

This chapter reviews evidence that the orthographic forms (spellings) of L2 sounds and words affect L2 phonological representation and processing. Orthographic effects are found in speech perception, speech production, phonological awareness, and the learning of words and sounds. Orthographic forms facilitate L2 speakers/listeners – for instance in lexical learning – but also have negative effects, resulting in sound additions, deletions, and substitutions. This happens because L2 speakers’ L2 orthographic knowledge differs from the actual working of the L2 writing system. Orthographic effects are established after little exposure to orthographic forms, are persistent, can be reinforced by factors other than orthography, including spoken input, and are modulated by individual-level and sound/word-level variables. Future research should address gaps in current knowledge, for instance investigating the effects of teaching interventions, and aim at producing a coherent framework.

This chapter outlines studies within the domain of speech perception by bilingual adult listeners. I first discuss studies that have examined bilinguals’ perception of L1 and/or L2 speech segments, as well as those that have tested perception of unfamiliar, non-native speech segments. In turn, I examine each of the factors that are known to affect bilinguals’ perception of speech, which include age of L2 acquisition, effects of L1:L2 usage as they pertain to language dominance and proficiency, and short-term contextual effects on speech perception. I also provide an overview of the literature on bilinguals’ perception of suprasegmentals. Finally, I explore what I think are some of the crucial questions facing the field of bilingual speech perception.

This chapter provides a cross-sectional overview of current neuroimaging techniques and signals used to investigate the processing of linguistically relevant speech units in the bilingual brain. These techniques are reviewed in the light of important contributions to the understanding of perceptual and production processes in different bilingual populations. The chapter is structured as follows. First, we discuss several non-invasive technologies that provide unique insights in the study of bilingual phonetics and phonology. This introductory section is followed by a brief review of the key brain regions and pathways that support the perception and production of speech units. Next, we discuss the neuromodulatory effects of different bilingual experiences on these brain regions from shorter to longer neural latencies and timescales. As we will show, bilingualism can significantly alter the time course, strength, and nature of the neural responses to speech, when compared with monolinguals.

This chapter introduces chief postulates common to usage-based (UB) approaches to language. The UB approach maintains that speakers’ experiences with language shape how language is stored. Experiences with specific words and word combinations in particular linguistic, discursive, and social contexts accrue in memory and subsequently contribute to patterns of variability evident in speech productions. Usage-based approaches regularly consider independent effects on lexical representations of decontextualized prior probabilities (e.g. phone/word/bigram frequencies, type frequencies), and, increasingly, contextually informed counts (e.g. lexical items’ cumulative exposure to conditioning effects of the production contexts, phone/word probabilities) are considered. This chapter offers an overview of studies exploring the connection between usage patterns and bilingual sound systems as well as studies exploring evidence of interlingual influence arising from bilingual lexical storage (schematic ties in memory). The chapter suggests potential avenues for future UB research into bilingual phonetics and phonology.

Computational models allow researchers to formulate explicit theories of language acquisition, and to test these theories against natural language corpora. This chapter puts the problem of bilingual phonetic and phonological acquisition in a computational perspective. The main goal of the chapter is to show how computational modeling can be used to address crucial questions regarding bilingual phonetic and phonological acquisition, which would be difficult to address with other experimental methods. The chapter first provides a general introduction to computational modeling, using a simplified model of phonotactic learning as an example to illustrate the main methodological issues. The chapter then gives an overview of recent studies that have begun to address the computational modeling of bilingual phonetic and phonological acquisition, focusing on phonetic and phonological cues for bilingual input separation, bilingual phonology in computational models of speech comprehension, and computational models of L2 speech perception. The chapter concludes by discussing several key challenges in the development of computational models of bilingual phonetic and phonological acquisition.

Evidence that listeners attend to and track subphonemic phonetic details is indicated by listeners’ ability to reliably connect subphonemic variation and, often, socio-indexical associations in ways that align with the patterns realized in production. Bilinguals are presented with the task not only of associating within-language variation (e.g., social group X is connected to a particular range of phonetic realizations within language Y) but also of attending to how ethnolects and bilingually accented speech index social categories across languages. Having access to multiple languages also gives bilingual speakers a larger repertoire with which to index language- and community-specific social meaning. This chapter outlines the linguistic structures bilinguals may connect across their languages and then presents a specific exemplar model, noting the opportunities within the model’s structure for bilingual dynamics. The heterogeneity of bilingual individuals and speech communities is necessarily addressed, as this dynamic adds to the complexity and intrigue of studying bilingual populations.

This chapter reviews the last twenty-five years of L2 prosody research in three sections, word stress, sentence intonation, and rhythm, and presents findings in relation to two underlying themes, form-meaning mapping and additive versus subtractive bilingual contexts. Concerning L2 stress, pioneering research framed perception difficulties either as an L1-to-L2 cue-transfer problem or as a processing deficit linked to learners’ inability to represent contrastive stress in their lexicons. Recent research established the extent and limits of those initial frames. L2 sentence intonation has multiple factors modeling its variation. One of them, social meaning, and in particular accommodation literature revealed the effect of affective factors which in multilingual communities became stronger than that of linguistic and social factors. As regards L2 rhythm, most research uses duration-based measures. Indeed, recent L1 studies started examining pitch-based rhythm measures which are still to be explored in L2. Ending with suggestions for future research that address those biases, this chapter aims at promoting a more inclusive and comprehensive understanding of L2 prosody.

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.

In this chapter, we thoroughly describe the L2LP model, its five ingredients to explain speech development from first contact with a language or dialect (initial state) to proficiency comparable to a native speaker of the language or dialect (ultimate attainment), and its empirical, computational, and statistical method. We present recent studies comparing different types of bilinguals (simultaneous and sequential) and explaining their differential levels of ultimate attainment in different learning scenarios. We also show that although the model has the word “perception” in its name, it was designed to also explain phonological development in general, including lexical development, speech production, and orthographic effects. The chapter demonstrates that the L2LP model can be regarded as a comprehensive theoretical, computational, and probabilistic model or framework for explaining how we learn the phonetics and phonology of multiple languages (sequentially or simultaneously) with variable levels of language input throughout the life span.