In this chapter, the ways that sign language phonology and prosodic structure interface with the other components of the grammar will be described, including how the nondominant hand interacts with morpho-syntactic and prosodic constituency. The most novel of the interfaces that will be discussed in this chapter will be the gesture–language interface, but the phonetics–phonology, morphology–phonology, and syntax/semantics–phonology interfaces will be discussed as well. This chapter also describes the details of higher-order prosodic structure not defined in earlier chapters – the phonological word (P-word; also referred to as the prosodic word), phonological phrase (P-phrase), and intonational phrase (I-phrase) – and provides evidence for prosody as independent from the rest of the grammar. This is of paramount importance because, in addition to showing how various components are interconnected, mismatches among different autonomous components of the grammar are one way we know that those components exist.

In this chapter, issues concerning the emergence of phonology will be addressed by tracing the paths of phonology and morphophonology as they move from gesture, to homesign, and across multiple stages in cohorts (or generations) of young sign languages. The material covered in the first four chapters of this volume will provide theoretical context for the emergence of phonology. Relevant work on spoken languages, which has observed and modeled processes of emergence or mapped them typologically, will be discussed, and some of the principles of phonological systems will be articulated, such as paradigm uniformity, conventionalization, symmetry of the phonological inventory, and well-formedness constraints on phonological constituents. Based on ongoing work we can also address some of the social factors that may be important in different rates of emergence in different social contexts or “language ecologies.”

Phonological acquisition and the milestones associated with it have been an important testing ground for theoretical claims since the inception of generative phonology, and the theme of this chapter builds on those from previous chapters. We have described how a sign language phonological system is influenced by the visual modality and by iconicity, how it is processed and how it emerges. We now add data from sign language acquisition to this picture, asking what evidence there is for the units proposed so far in the phonological system of a child or infant.

Typical first-language (L1) phonological acquisition is a critical piece in any child’s development as she makes contact with the world, and as we will see, it is also an important stepping-stone for reading. We also address acquisition in several other circumstances where sign language is acquired, as it pertains to second-language (L2) learners, late learners of an L1, and bilingual development. These populations are unique in ways that will become clear as they are introduced throughout the chapter.

There are numerous differences between signed and spoken languages due to the different communication modalities they use, but which ones actually matter for phonology? In this chapter, a range of differences will be laid out: environmental ones, those that depend on the signal, and those related to phonetic and phonological forms. Through the course of this discussion we will see that, despite the major differences between the visual-gestural and auditory-vocal systems used in the two types of languages, many of the same abstract mechanisms are employed by signed and spoken languages.

In this chapter, the ways that iconicity and phonological constraints work together in sign languages will be described. Different types of iconicity will be delineated, and then a number of examples will be provided of how the phonetic pressures of ease of articulation, ease of perception, and iconicity conspire in sign language phonology. Iconicity is pervasive in sign languages, which makes these languages fertile ground for research on the topic, and it offers a way for work on sign languages to make a contribution to linguistic theory more broadly.

By working through phonological questions using sign language data we arrive at a new understanding of the very nature of phonology, of the very nature of language. This chapter gives a brief historical look into the field from its inception, lays out the reasons why thinking about sign language phonology opens up new ways to understand the nature of language, broadly construed, and provides enough background on the units of word-level phonology in sign languages to see practical and theoretical connections to parallel issues in spoken language phonology.

This chapter covers factors that affect variation in phonological or prosodic form synchronically and diachronically. Such factors can include grammatical context, phonetic factors such as ease of articulation and perception, as well as a range of sociolinguistic factors, such as age, gender, region, and ethnicity.

Is phonological form perceived, understood, stored, and accessed in the same way and with the same neural mapping in signed and spoken languages? This is the complex and multifaceted question that the work on sign language processing has addressed since the beginning. The methodologies and technologies used to address this question have become more sophisticated over the last sixty years. Since the beginning, a psycholinguistic tradition was at the center of the work on sign languages, and we trace the trajectory of this work in this chapter.