This aim of this thesis is to give a phonological account of acoustic variation and reduction. It is argued that phonological representations are uneven and include information about the relative strength of the segmental and subsegmental units composing them. This unevenness implies a distinction between the invariant – the “phonetic essence” of a word, which is practically undeletable – and other units which can be dispensed with under certain circumstances. In the first chapter I compare different theoretical approaches to the problem of acoustic variation, in particular with reference to generative phonology and exemplar-based theories. In the second chapter I propose a model which combines aspects of Optimality Theory, Element Theory and usage-based linguistics. Additionally, I discuss the role of acoustic salience in the formation of the invariant. In chapter three, typological and experimental data are examined in order to establish a salience scale for consonants. In chapter four, the results of the acoustic analysis of four dialogues extracted from a corpus of spoken Italian are presented. As expected, highly salient consonants are preserved to a greater extent than less salient ones. In chapter five I attempt to identify the phonological correlates of acoustic salience and discuss other factors which may favor reduction and deletion, among which predictability. In chapter six I draw some conclusions, deal with some pending issues and suggest future directions for research
