Statistical Language Modeling for Speech Disfluencies

Andreas Stolcke - Elizabeth Shriberg
Speech Technology and Research Laboratory
SRI International, Menlo Park, CA 94025
stolcke@speech.sri.com
ees@speech.sri.com

Abstract:

Speech disfluencies (such as filled pauses, repetitions, restarts) are among the characteristics distinguishing spontaneous speech from planned or read speech. We introduce a language model that predicts disfluencies probabilistically and uses an edited, fluent context to predict following words. The model is based on a generalization of the standard N-gram language model. It uses dynamic programming to compute the probability of a word sequence, taking into account possible hidden disfluency events. We analyze the model's performance for various disfluency types on the Switchboard corpus. We find that the model reduces word perplexity in the neighborhood of disfluency events; however, overall differences are small and have no significant impact on recognition accuracy. We also note that for modeling of the most frequent type of disfluency, filled pauses, a segmentation of utterances into linguistic (rather than acoustic) units is required. Our analysis illustrates a generally useful technique for language model evaluation based on local perplexity comparisons.

• Motivation and Overview
• The Model
  • Disfluency types
  • The Cleanup Model
  • Probability computation
  • Estimation
• Results and Analysis
  • Overall results
  • Analysis by DF type
    • Filled pauses
    • Repetitions
    • Deletions
  • Filled pauses and utterance segmentation
  • Results from related work
• Discussion and Conclusions
• References
• About this document ...