A Constraint-based Approach to English Prosodic Constituents

A Constraint-based Approach to English Prosodic Constituents Ewan Klein Division of Informatics University of Edinburgh 2 Buccleuch Place, Edinburgh EH8 9LW, UK ewan@cogsci.ed.ac.uk Abstract The paper develops a constraint-based the- ory of prosodic phrasing and prominence, based on an HPSG framework, with an implementation in ALE. Prominence and juncture are represented by n-ary branching metrical trees. The general aim is to define prosodic structures recursively, in parallel with the definition of syntactic structures. We address a number of prima facie problems arising from the discrepancy between syntactic and prosodic structure 1 Introduction This paper develops a declarative treatment of pros- odic constituents within the framework of constraint- based phonology, as developed for example in (Bird, 1995; Mastroianni and Carpenter, 1994). On such an approach, phonological representations are encoded with typed feature terms. In addition to the representational power of complex feature values, the inheritance hierarchy of types provides a flexible mechanism for classifying linguistic structures, and for expressing generalizations by means of type inference. To date, little work within constraint-based phono- logy has addressed prosodic structure above the level of the foot. In my treatment, I will adopt the following assumptions: 1. Phonology is induced in parallel with syntactic structure, rather than being mapped from pre- built parse trees. 2. Individual lexical items do not impose constraints on their neighbour’s phonology. The first of these assumptions ensures that phonology is compositional, in the sense that the only information available when assembling the phonology of a com- plex constituent is the phonology of that constituents daughters. The second assumption is one that is standardly adopted in HPSG (Pollard and Sag, 1994), in the sense that heads can be subcategorized with respect to the syntactic and semantic properties of their arguments (i.e., their arguments’ synsem values), but not with respect to their arguments’ phonological properties. Although I am not convinced that this restriction is correct, it is worthwhile to explore what kinds of phonological analyses are compatible with it. Most of the data used in this paper was drawn from the SOLE spoken corpus (Hitzeman et al., 1998).1 The corpus was based on recordings of one speaker reading approximately 40 short descriptive texts concerning jewelry. 2 Syntactic and Prosodic Structure 2.1 Metrical Trees Metrical trees were introduced by Liberman (1977) as a basis for formulating stress-assignment rules in both words and phrases. Syntactic constituents are assigned relative prosodic weight according to the following rule: (1) NSR: In a configuration [C A B], if C is a phrasal category, B is strong. Prominence is taken to be a relational notion: constituent labelled ‘s’ is stronger than its sister.a Consequently, if B in (1) is strong, then A must be weak. In the case of a tree like (2), Liberman and Prince’s (1) yields a binary-branching structure of the kind illustrated in (3) (where the root of the tree is unlabeled): (2) VP V fasten NP Det a N cloak 1The task of recovering relevant examples from the SOLE corpus was considerably aided by …

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