A fast lattice-based approach to vocabulary independent wordspotting

Practical applications of wordspotting, such as spoken message retrieval and browsing, require the ability to process large amounts of speech data at speeds many times faster than real-time. This paper presents a novel approach to this problem in which all of the stored audio material is prepro-cessed oo-line to generate a phoneme lattice. At search time, putative word matches are found in this lattice using symmetric dynamic programming. The paper presents the details of the algorithms used and compares performance with a number of conventional approaches using a 20 keyword vocabulary on the DARPA Resource Management Task. The results show that the proposed method is very much faster yet performs acceptably compared to conventional systems which depend on keyword-speciic training or prior knowledge of the test set vocabulary.