Showing papers by "R. De Mori published in 2007"

Spoken Language Understanding Strategies on the France Telecom 3000 Voice Agency Corpus

Abstract: Telephone services are now deployed that allow users to react to telephone prompts in spoken natural language. These systems have limited domain semantics and dialogue strategies which are represented by finite state diagrams. Most of these systems adopt a sequential approach where the automatic speech recognition (ASR) process, the spoken language understanding (SLU) process and the dialogue management (DM) are separate processes. In the framework of the France Telecom 3000 voice service, we propose in this paper to study several strategies in order to integrate more closely these three processes: ASR, SLU, and DM. By means of a finite state machine paradigm encoding the different models used by these three levels we show how the search for the best sequence of dialogue states can be done simultaneously at the word, concept, interpretation and dialogue state levels.

Sequential Decision Strategies for Machine Interpretation of Speech

Abstract: Recognition errors made by automatic speech recognition (ASR) systems may not prevent the development of useful dialogue applications if the interpretation strategy has an introspection capability for evaluating the reliability of the results. This paper proposes an interpretation strategy which is particularly effective when applications are developed with a training corpus of moderate size. From the lattice of word hypotheses generated by an ASR system, a short list of conceptual structures is obtained with a set of finite state machines (FSM). Interpretation or a rejection decision is then performed by a tree-based strategy. The nodes of the tree correspond to elaboration-decision units containing a redundant set of classifiers. A decision tree based and two large margin classifiers are trained with a development set to become interpretation knowledge sources. Discriminative training of the classifiers selects linguistic and confidence-based features for contributing to a cooperative assessment of the reliability of an interpretation. Such an assessment leads to the definition of a limited number of reliability states. The probability that a proposed interpretation is correct is provided by its reliability state and transmitted to the dialogue manager. Experimental results are presented for a telephone service application