We present recent advances from our efforts in increasing coverage, robustness, generality and speed of JANUS, CMU's speech-tospeech translation system. JANUS is a speaker-independent system translating spoken utterances in English and also in German into one of German, English or Japanese. The system has been designed around the task of conference registration (CR). It has initially been built based on a speech database of 12 read dialogs, encompassing a vocabulary of around 500 words. We have since been expanding the system along several dimensions to improve speed, robustness and coverage and to move toward spontaneous input. 1. INTRODUCTION In this paper we describe recent improvements of JANUS, a speech to speech translation system. Improvements have been made mainly along the following dimensions: 1.) better context-dependent modeling improves performance in the speech recognition module, 2.) improved language models, smoothing, and word equivalence classes improve coverage and ...

The paper describes a new implementation of feature structures containing disjunctive values, which can be characterized by the following main points: Local representation of embedded disjunctions, avoidance of expansion to disjunctive normal form and of repeated test-unifications for checking consistence. The method is based on a modification of Kasper and Rounds' calculus of feature descriptions and its correctness therefore is easy to see. It can handle cyclic structures and has been incorporated successfully into an environment for grammar development.