Draft Text about Computing Infrastructure for future ProSynth proposal

1.	Background: Existing Tools

The computational infrastructure for the project will build on the tools developed in the first two ProSynth projects.  The ProSynth synthesis system is an open architecture for synthesis which uses a chain of simple programs and scripts to flesh out a linguistic description of an utterance expressed in XML.  Input to the system is marked-up text, and output is compatible with a range of signal generation components, including MBROLA, Festival, BT Laureate, and HLSYN, as well as prosody manipulated natural speech.  The aim has been to treat synthesis as interpretation, where the context in which a component occurs (established either by its position in the linguistic structure or explicitly by markup) controls the form that it is realised.  A simple scripting language called ProXML was developed to express knowledge about interpretation in a declarative formalism which is easier to enhance and maintain than a set of interacting rules.  This software is publicly available.

The previous projects used other statistical tools for data analysis, including CART, GLM and functional approximation tools.  The results of these analyses were however always expressed in the ProXML formalism.

2.	Development of Tools

Unit-selection synthesis:

A weakness of the current tools are their lack of support for corpus-based synthesis tools using a unit selection algorithm based on prosodic and phonetic features.  To evaluate the phonetic representations we develop on this project, we shall implement a unit-selection based synthesis system for English.  This will use the open-source unit-selection system under development by Stöbler et al at the University of Bonn, in combination with our existing ProSynth databases of read speech.  This system  will allow us to store and retrieve signal sections according to a range of possible parameters, both prosodic and phonetic, and to concatenate and smooth the result.  This tool can then be used to investigate the effectiveness of our phonetic interpretations for unit selection.
 
Linguistic Markup:

The project will involve much more text-level markup than the previous projects.  This means that mechanisms will need to be developed to pass information expressed as operators on words or word strings down into the prosodic hierarchy.  We would like to do this in a principled way, rather than by confusing levels by using phonological markup on the word strings.  Thus we would avoid markup schemes which added pitch accent types to words, or indicated prosodic phrasing at the word level.  Text markup should instead be related to properties of words or consituents with regard to information structure.

MAH
23 November 2000