A Parser for Real-Time Speech Synthesis of Conversational Texts

A PARSER FOR REAL-TIME SPEECH SYNTHESIS OF CONVERSATIONAL TEXTS Joan Bachenko Jeffrey Daugherty t Eileen Fitzpatrick AT&T Bell Laboratories Murray Hill, NJ 07974 ABSTRACT In this paper, we concern ourselves with an applica- tion of text-to-speech for speech-impaired, deaf, and hard of hearing people. The application is unusual because it requires real-time synthesis of unedited, spontaneously generated conversational texts transmitted via a Telecommunications Device for the Deaf (TDD). We describe a parser that we have implemented as a front end for a version of the Bell Laboratories text-to-speech synthesizer (Olive and Liberman 1985). The parser prepares TDD texts for synthesis by (a) performing lexical regularization of abbreviations and some non-standard forms, and (b) identifying prosodic phrase boundaries. Rules for identifying phrase boundaries are derived from the prosodic phrase grammar described in Bachenko and Fitzpatrick (1990). Following the parent analysis, these rules use a mix of syntactic and phonological factors to identify phrase boundaries but, unlike the parent system, they forgo building any hierarchical structure in order to bypass the need for a stacking mechanism; this permits the system to operate in near real time. As a component of the text-to-speech system, the parser has undergone rigorous testing during a successful three-month field trial at an AT&T telecommunications center in California. In addition, laboratory evaluations indicate that the parser's performance compares favorably with human judgments about phrasing. 1. INTRODUCTION Text-to-speech researchers and developers tend to assume that applications of their technology will focus on edited text, either "canned" material such as name and address lists, or free text like the AP newswire. There has been much effort aimed at preparing text-to-speech for appli- cations such as caller identification and newsreading services, in which texts are generally proofed and the pri- mary challenges come from issues of name pronuncia- tion, intonation contouring, etc. In this paper, we con- cern ourselves with an application of text-to-speech for speech-impaired, deaf, ~md hard of hearing people. The application is unusual because it requires text-to-speech synthesis of unedited, spontaneously generated conversa- tional text. Moreover the synthesis must occur in near real time as the user is typing. We will describe a parser that prepares conversational texts for synthesis by first performing lexical regulariza- tion of nonstandard forms and then identifying prosodic phrase boundaries. The parser is derived from the pro- sodic phrase system presented in Bachenko and Fitzpa- trick (1990) and has been implemented as the front end of a version of the Bell Laboratories text-to-speech syn- thesizer (Olive and Liberman 1985). As a component of the text-to-speech system, the parser has undergone rigorous testing during a successful three-month field trial at an AT&T telecommunications center in Califor- nia. In addition, laboratory evaluations indicate that the parser's performance compares favorably with human judgments about phrasing. In Section 2 of the paper we describe the application and the texts. Section 3 provides a technical description of the parser and Section 4 discusses evaluation of the parser's performance. 2. THE APPLICATION Users of Telecommunications Devices for the Deaf …

Content truncated to 500 words