Word spotting based on a posterior measure of keyword confidence

  • Authors:
  • Hao Jie;Li Xing

  • Affiliations:
  • Department of Electronic Engineering, Tsinghua University, Beijing 100084, P.R. China;Department of Electronic Engineering, Tsinghua University, Beijing 100084, P.R. China

  • Venue:
  • Journal of Computer Science and Technology
  • Year:
  • 2002

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Abstract

In this paper, an approach of keyword confidence estimation is developed that well combines acoustic layer scores and syllable-based statistical language model (LM) scores. An a posteriori (AP) confidence measure and its forward-backward calculating algorithm are deduced. A zero false alarm (ZFA) assumption is proposed for evaluating relative confidence measures by word spotting task. In a word spotting experiment with a vocabulary of 240 keywords, the keyword accuracy under the AP measure is above 94%, which well approaches its theoretical upper limit. In addition, a syllable lattice Hidden Markov Model (SLHMM) is formulated and a unified view of confidence estimation, word spotting, optimal path search, and N-best syllable re-scoring is presented. The proposed AP measure can be easily applied to various speech recognition systems as well.