UK-German Funding Initiative in the Humanities: Prosodic structure at the interface between language and speech

Both language redundancy and prosodic structure affect characteristics of speech related to acoustic salience and intelligibility. Proposals that prosodic structure is the interface between grammar and speech led Aylett and Turk (2004, 2006) and Turk (2010) to propose that speakers plan the prosodic structure of an utterance in order to make less predictable parts of speech more intelligible via its effects on acoustic saliency (the Smooth Signal Redundancy Hypothesis, Aylett 2000).

The goals of this project are 1) to test the hypothesis that prosodic structure is the interface between language and speech, and 2) to implement this interface in a (computational) model of grammar in order to test and evaluate our architectural assumptions. A prediction of the Prosodic Interface Hypothesis is that different types of language redundancy (predictability) measures should have similar effects on speech acoustics, e.g., on the fundamental frequency and duration. That is, they should all affect properties and parts of words that relate to prosodic prominence and boundary strength. The first strand of the project tests the effects of repetition, length, syntactic, word-bigram, word frequency, and pragmatic language redundancy measures on pauses and speech acoustics in relevant parts of words, and compares these effects to known effects of prosodic prominence and boundary strength. The second strand of the project involves modelling the effects of the first part within Lexical Functional Grammar (LFG). The modular correspondence architecture of LFG provides an optimal theoretical framework that allows for an interaction between different aspects of grammar. By means of an implementation in a computational LFG grammar, we intend to test the formal model in its complete range from the semantic analysis to the speech signal, and to extend the framework to model the influence of frequency and other predictability effects on a gradient representation of prosodic structure.