Latent semantic retrieval of spoken documents over position specific posterior lattices

This paper presents a new approach of latent semantic retrieval of spoken documents over Position Specific Posterior Lattices (PSPL). This approach performs concept matching instead of literal term matching during retrieval based on the Probabilistic Latent Semantic Analysis (PLSA), so as to solve the problem of term mismatch between the query and the desired spoken documents. This approach is performed over PSPL to consider the multiple hypotheses generated by ASR process, as well as the position information for these hypotheses, so as to alleviate the problem of relatively poor ASR accuracy. We establish a framework to evaluate semantic relevance between terms and the relevance score between a query and a PSPL, both based on the latent topic information from PLSA. Preliminary experiments on Chinese broadcast news segments showed significant improvements can be obtained with the proposed approach.