Position Specific Posterior Lattices (PSPL) have been recently proposed as very powerful, compact structures for indexing speech. In this paper, we take PSPL one step further to Subword-based Position Specific Posterior Lattices (S-PSPL). As with PSPL, we include posterior probabilities and proximity information, but we base this information on subword units rather than words. The advantages of S-PSPL over PSPL mainly come from rare and/or OOV words, which may be included in S-PSPL but generally are not in PSPL. Experiments on Mandarin Chinese broadcast news showed significant improvements from S-PSPL as compared to PSPL. Such advantages are believed to be language independent.
Bibliographic reference. Pan, Yi-cheng / Chang, Hung-lin / Chen, Berlin / Lee, Lin-shan (2007): "Subword-based position specific posterior lattices (s-PSPL) for indexing speech information", In INTERSPEECH-2007, 318-321.