Lightweight Spoken Utterance Classification with CFG, tf-idf and Dynamic Programming

  • Manny RaynerEmail author
  • Nikos Tsourakis
  • Johanna Gerlach
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10583)


We describe a simple spoken utterance classification method suitable for data-sparse domains which can be approximately described by CFG grammars. The central idea is to perform robust matching of CFG rules against output from a large-vocabulary recogniser, using a dynamic programming method which optimises the tf-idf score of the matched grammar string. We present results of experiments carried out on a substantial CFG-based medical speech translator and the publicly available Spoken CALL Shared Task. Robust utterance classification using the tf-idf method strongly outperforms plain CFG-based recognition for both domains. When comparing with Naive Bayes classifiers trained on data sampled from the CFG grammars, the tf-idf/dynamic programming method is much better on the complex speech translation domain, but worse on the simple Spoken CALL Shared Task domain.


Speech recognition Spoken utterance classification Robustness Context-free grammar tf-idf Medical applications 


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Manny Rayner
    • 1
    Email author
  • Nikos Tsourakis
    • 1
  • Johanna Gerlach
    • 1
  1. 1.TIM/FTIUniversity of GenevaGenevaSwitzerland

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