Discriminative lexicon adaptation for improved character accuracy: a new direction in Chinese language modeling

  • Authors:
  • Yi-cheng Pan;Lin-shan Lee;Sadaoki Furui

  • Affiliations:
  • National Taiwan University, Taipei, Taiwan;National Taiwan University, Taipei, Taiwan;Tokyo Institute of Technology, Tokyo, Japan

  • Venue:
  • ACL '09 Proceedings of the Joint Conference of the 47th Annual Meeting of the ACL and the 4th International Joint Conference on Natural Language Processing of the AFNLP: Volume 2 - Volume 2
  • Year:
  • 2009

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Abstract

While OOV is always a problem for most languages in ASR, in the Chinese case the problem can be avoided by utilizing character n-grams and moderate performances can be obtained. However, character n-gram has its own limitation and proper addition of new words can increase the ASR performance. Here we propose a discriminative lexicon adaptation approach for improved character accuracy, which not only adds new words but also deletes some words from the current lexicon. Different from other lexicon adaptation approaches, we consider the acoustic features and make our lexicon adaptation criterion consistent with that in the decoding process. The proposed approach not only improves the ASR character accuracy but also significantly enhances the performance of a character-based spoken document retrieval system.