Paper: Speech OGLE: Indexing Uncertainty For Spoken Document Search

ACL ID P05-3011
Title Speech OGLE: Indexing Uncertainty For Spoken Document Search
Venue Annual Meeting of the Association of Computational Linguistics
Session System Demonstration
Year 2005

The paper presents the Position Specific Posterior Lattice (PSPL), a novel lossy representation of automatic speech recog- nition lattices that naturally lends itself to efficient indexing and subsequent rele- vance ranking of spoken documents. In experiments performed on a collec- tion of lecture recordings — MIT iCam- pus data — the spoken document rank- ing accuracy was improved by 20% rela- tive over the commonly used baseline of indexing the 1-best output from an auto- matic speech recognizer. The inverted index built from PSPL lat- tices is compact — about 20% of the size of 3-gram ASR lattices and 3% of the size of the uncompressed speech — and it al- lows for extremely fast retrieval. Further- more, little degradation in performance is observed when pruning PSPL lattices, r...