GAIA : A Software Platform for the Integration of Speech Translation Techonologies

We present here an open-source software platform for the integration of speech translation components. This tool is useful to integrate into a common framework different automatic speech recognition, spoken language translation and text-to-speech synthesis solutions. The Gaia platform is also utile in the task of obtaining the text and speech corpora needed when performing speech translation. The platform follows a modular distributed approach, with a specifically designed extensible network protocol handling the communication with the different servers. This facilitates the integration of existing solutions into the architecture. The software is provided together with completely functional audio (telephone or microphone) and text clients. Remote configuration and monitoring is possible with standard Java compliant browsers. Gaia has been successfully used in the European LC-STAR and the national ALIADO projects. 1. Spoken Language Translation Multilingual human to human communication using machines is an area of investigation being actively developed. Different technologies are involved in the translation of speech, namely Automatic Speech Recognition (ASR), Spoken Language Translation (SLT) and Text-To-Speech synthesis (TTS). Several projects are currently under development or have recently been finished that make use of these technologies: ALIADO [1], C-STAR [2], FAME [3], VERBMOBIL [4], CHIL [5], TC-STAR [6] or LC-STAR [7]. The development of the Gaia platform is embedded into this last one. LC-STAR was started in February 1st, 2002 and focuses on the creation of language resources for transferring Speech-to-Speech Translation components. The goal of the project is to improve human-to-human and person-machine communication in multilingual environments. It aims to create lexica and corpora needed for flexible vocabulary speech recognition, speech centered translation into selected languages and high-quality speech synthesis. Two parallel tracks address the different maturity of speech-to-speech translation components. The goal of the first track is to develop pronunciation lexica for each of the 12 languages, consisting of 50000 common word entries and 50000 proper names entries each. The second track includes the development of corpora and language resources needed for speech-to-speech translation, and the creation of a baseline system. Among the different subtasks defined in this track, a demonstration system to show the language transfer is proposed: the Gaia platform. The rest of this paper is devoted to the architecture of the software and the different scenarios where it can be used. 2. Architecture The platform structure follows a modular design, with different parts running in separate machines. The speech processing tasks (recognition, translation and synthesis) are implemented in independent servers, communicating with the platform kernel via standard network sockets. Distribution is mandatory since each task can be computationally demanding. Moreover, it allows the different partners to implement their particular solutions in different platforms if desired, achieving a high grade of flexibility. Two different paradigms could be followed. If designed as single entity, with the different client interfaces, the recognition, translation and synthesis engines, and the platform kernel would be objects or components of a single software program. In this case, several distributed computing models exist that permit components to be spread across multiple computers: CORBA (Common Object Request Broker Architecture)[8] or OOA (Open Agent Architecture) [9] among others. The later is the paradigm followed in the related CHIL [5] project, aimed at the exploration and creation of environments in which computers are used in human to human communication. On the other hand, if instead of as components each part is conceived as an entity in itself, with the ability or requirement to run independently of the platform, a client/server approach could be followed. Hence, the different parts of the platform are implemented as independent programs, using standard sockets and a predefined network protocol to communicate with the different modules of the system. This is the approach followed in the Galaxy [10] project at MIT or in the concluded national Spanish project BASURDE [11] among others. The development of the Gaia platform follows this last paradigm, since our interest is to integrate existing solutions into a common framework. Figure 1 shows the different modules of the platform and its distribution across a network environment.