Subword-based position specific posterior lattices (s-PSPL) for indexing speech information

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.