5th International Conference on Spoken Language Processing

Sydney, Australia
November 30 - December 4, 1998

Reducing Peak Search Effort Using Two-Tier Pruning

Mark Wright, Simon Hovell, Simon Ringland

BT Laboratories, UK

Many of the pruning strategies used to remove less likely hypotheses from the search space in large vocabulary speech recognition (LVR) systems, have a peak search space many times greater than the average search space. This paper discusses two such strategies used within BT's speech recognition architecture, Step pruning and Histogram pruning. Two-tier pruning is proposed as a simple but powerful extension applicable to either of the above strategies. This seeks to limit the expansion of the search space between the prune and acoustic match processes without affecting accuracy. It is shown that the application of two-tier pruning to either strategy reduces peak search effort, and results in an average reduction in run time of 33% and 53% for step pruning and histogram pruning respectively, with no loss in top-N accuracy.

Full Paper

Bibliographic reference.  Wright, Mark / Hovell, Simon / Ringland, Simon (1998): "Reducing peak search effort using two-tier pruning", In ICSLP-1998, paper 0450.