ABSTRACT
This chapter discusses the constraints problem and the actual mechanisms of sound change. Prototypical sound changes involve phonologisation, in which a direct link can be found between a change and some automatic phonetic process: a precursor. Words change phonological form in ways that are variously similar and dissimilar to prototypical cases of phonologisation. Certain processes were traditionally excluded from precursor-based sound change, because linguists saw no precursor articulatory patterns that might generate them. If the key Neogrammarian insight was to distinguish between sound changes and analogical changes, then changes like those in may not bear on the properties of the former. The embedding problem involves questions about the relation between a change and its social and linguistic contexts. American structuralist discussions of sound change often emphasised how changes affect phonemic systems. Phonological embedding is intensely debated in current research. The initiation of sound change also raises the broader actuation problem of Weinreich et al.
