Sixth European Conference on Speech Communication and Technology

Budapest, Hungary
September 5-9, 1999

A Comparison of Word Graph and N-Best List Based Confidence Measures

Frank Wessel, Klaus Macherey, Hermann Ney

Lehrstuhl für Informatik VI, RWTH Aachen - University of Technology, Aachen, Germany

In this paper we present and compare several confidence mea-sures for large vocabulary continuous speech recognition. We show that posterior word probabilities computed on word graphs and N-best lists clearly outperform non-probabilistic confidence measures, e.g. the acoustic stability and the hypothesis density. In addition, we prove that the estimation of posterior word prob-abilities on word graphs yields better results than their estimation on N-best lists and discuss both methods in detail. We present experimental results on three different corpora, the English NAB ’94 20k development corpus, the German VERBMOBIL ’96 evaluation corpus and a Dutch corpus, which has been recorded with a train timetable information system in the ARISE project.

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Bibliographic reference.  Wessel, Frank / Macherey, Klaus / Ney, Hermann (1999): "A comparison of word graph and n-best list based confidence measures", In EUROSPEECH'99, 315-318.