In human languages, the realisation of phonemes can be influenced by several factors, thus resulting in different output forms. Specifically, in certain phonological environments, a phoneme (or a set of phonemes) can be subject to manipulations, which are due to the application of so-called phonological processes. These can be defined as rules or constraints that determine how phonemes are to be produced in a given phonological environment.
Generally speaking, in sign languages the implementation of phonological processes might be motivated by the need to maximize either ease of articulation or ease of perception. In other cases, they might be used to adapt loan signs (LEXICON 2) to the phonemic inventory of the target language. They can also result from the application of morphological processes, such as compounding, or syntactic reasons. Phonological processes can apply to different domains: phoneme, syllable, prosodic word, etc. Their occurrence can be obligatory or optional: that is, some of them are always applied by signers, while others might depend on other factors, such as the formality-informality of the setting.
This chapter discusses the main phonological processes occurring in LIS, providing illustrative examples. For the sake of clarity, the different processes are grouped according to the phonological component affected by the process itself. Specifically, we describe processes affecting the phonemic level (PHONOLOGY 3.1), syllable (PHONOLOGY 3.2), prosodic word (PHONOLOGY 3.3) and higher prosodic units (PHONOLOGY 3.4). Note that this chapter mainly concentrates on those phonological processes occurring in the synchronic grammar, shared by LIS signers at present.