This paper describes a continuous speech recognition system using two-level LR parsing and phone based HMMs. ATR has already implemented a predictive LR parsing algorithm in an HMM-based speech recognition system for Japanese. However, up to now, this system has used only intra-phrase grammatical constraints. In Japanese, a sentence is composed of several phrases and thus, two kinds of grammars, namely an intra-phrase grammar and an inter-phrase grammar, are sufficient for recognizing sentences. Two-level LR parsing makes it possible to use not only intra-phrase grammatical constraints but also inter-phrase grammatical constraints during speech recognition. The system is applied to Japanese sentence recognition where sentences were uttered phrase by phrase, and attains a word accuracy of 95.9% and a sentence accuracy of 84.7%.

This paper describes issues on dialogue corpora for speech and natural language research. Speech and text corpora of dialogue have recently become more important for the development and the evaluation of speech and text-based dialogue systems. However, the design and the construction of dialogue corpora themselves still remain research issues and many problems have not yet been clarified. Many kinds of corpus are necessary to study various aspects of dialogues. On the other hand, each corpus should contain a certain quantity for each purpose in order to make it statistically meaningful. This paper presents the issues related with design and creation of dialogue corpora; the selection of a task domain, transcription conventions, situations for the collection, syntactic and semantic ill-formedness, and politeness. Future directions for dialogue corpora creation are also discussed.

In this paper we propose an objective method for assessing the capability of a speech translation system. It automates the translation paired comparison method, which gives a simple, easy to understand TOEIC score proposed by Sugaya et al., to succinctly evaluate a speech translation system. To avoid the expensive evaluation cost of the original method where large manual effort is required, the new objective method automates the procedure by employing an objective metric such as BLEU and DP-based measure. The evaluation results obtained by the proposed method are similar to those of the original method. Also, the proposed method is used to evaluate the usefulness of a speech translation system. It is then found that our speech translation system is useful in general, even to users with higher TOEIC score than the system's.