Efficient training of discriminative language models by sample selection

  • Authors:
  • Takanobu Oba;Takaaki Hori;Atsushi Nakamura

  • Affiliations:
  • NTT Communication Science Laboratories, NTT Corporation, 2-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan;NTT Communication Science Laboratories, NTT Corporation, 2-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan;NTT Communication Science Laboratories, NTT Corporation, 2-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan

  • Venue:
  • Speech Communication
  • Year:
  • 2012

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Abstract

This paper focuses on discriminative language models (DLMs) for large vocabulary speech recognition tasks. To train such models, we usually use a large number of hypotheses generated for each utterance by a speech recognizer, namely an n-best list or a lattice. Since the data size is large, we usually need a high-end machine or a large-scale distributed computation system consisting of many computers for model training. However, it is still unclear whether or not such a large number of sentence hypotheses are necessary. Furthermore, we do not know which kinds of sentences are necessary. In this paper, we show that we can generate a high performance model using small subsets of the n-best lists by choosing samples properly, i.e., we describe a sample selection method for DLMs. Sample selection reduces the memory footprint needed for holding training samples and allows us to train models in a standard machine. Furthermore, it enables us to generate a highly accurate model using various types of features. Specifically, experimental results show that even training using two samples in each list can provide an accurate model with a small memory footprint.