The phenomenon of acoustic-phonetic variability in the way
words, syllables and sound segments are produced in different
contexts in fluent continuous speech is well known, and raises
the question of whether this variability is governed by abstract
structures at higher levels. Evidence in support of this
possibility is Dound both in phonetic rules based on native
language user intuitions, and in measurements of phenomena
that are less accessible to intuition, such as preboundary
lengthening. Early investigations focussed on traditional
morphosyntactic structures, such as lexical words and syntactic
clauses and phrases, as candidates for the abstract structures
that might govern phonetic variability. In recent decades,
however, developments in the theory of prosody have provided
a new set of candidate structures in the form of the elements of
the prosodic hierarchy. These include constituent structures
such as utterances, intonational phrases, prosodic words etc., as
well as prominences such as nuclear and prenuclear pitch
accents. Evidence is accumulating that many aspects of
phonological and phonetic variation in spoken utterances are
systematic with respect to these prosodic structures. In this talk
we will explore the hypothesis that traditional morphosyntactic
structures influence the phonetic realization of words and
sounds indirectly, via their influence on the prosodic structures
that directly govern the phonetic choices that speakers make.
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