In the area of speech synthesis it is already possible to generate understandable speech with citation form prosody for simple written texts. However at ATR we are researching into speech synthesis techniques for use in a speech translation environment. Dialogues in such conversations involve much richer forms of prosodic variation than are required for the reading of texts. In order for our translations to sound natural it is necessary for our synthesis system to o er a wide range of prosodic variability, which can be described at an appropriate level of abstraction. This paper describes a multi-level intonation system which generates a fundamental frequency (F 0 ) contour based on input labelled with high level discourse information, including speech act type and focusing information, as well as part of speech and syntactic constituent structure. The system is rule driven but the rules and to some extent the levels themselves are derived from naturally spoken dialogues. This paper presents a framework for generating intonation parameters based on existing natural speech dialogues labelled with that intonation system, and marked with high level discourse features. The goal of this study is to predict the intonation of discourse segments in spoken dialogue for synthesis in a speech-translation system. Spontaneous spoken dialogue involves more use of intonational variety than does reading of written prose, so the intonation speci cation component of our speech synthesizer has to take into account the prosody of di erent speech act types, and must allow for the generation of utterances with the same variability as found in natural dialogue. For example the simple English word \okay" is heard often in conversation but performs di erent functions. Sometimes it has the meaning \I understand.", sometimes \do you understand?", other times it is used as a discourse marker indicating a change of topic, or as an end-of-turn marker signalling for the other partner to speak. Di erent uses of a word have di erent intonational tunes. Already there are a number of intonation systems which allow a speci cation of intonation at a higher level of abstraction than directly representing the fundamental frequency contour ( ToBI o ers a discrete symbolic representation of linguistic intonation patterns; while Tilt o ers a representation of physical pitch patterns, that di erence is not signi cant in this work. All these intonation systems o er a method of representation from which varied F0 contours may be generated. In this paper we are primarily concerned with a level of discourse intonation \above" these intonation systems. That is a system that will predict intonation parameters (for whatever intonation system being used) from higher level discourse information such as speech act, discourse function, syntactic structure and part of speech information. The following diagram positions this work in the process of generating a F 0 contour in speech synthesis.
REF presented a model for generating intonation patterns based on high-level discourse features automatically extracted from dialogue speech.
Predicting the Intonation of Discourse Segments From Examples in Dialogue Speech
ESCA/Aalborg University
Computer Science