INTERSPEECH 2009
10th Annual Conference of the International Speech Communication Association

Brighton, United Kingdom
September 6-10, 2009

Merging Search Spaces for Subword Spoken Term Detection

Timo Mertens (1), Daniel Schneider (2), Joachim Köhler (2)

(1) NTNU, Norway
(2) Fraunhofer IAIS, Germany

We describe how complementary search spaces, addressed by two different methods used in Spoken Term Detection (STD), can be merged for German subword STD. We propose fuzzy-search techniques on lattices to narrow the gap between subword and word retrieval. The first technique is based on an edit-distance, where no a priori knowledge about confusions is employed. Additionally, we propose a weighting method which explicitly models pronunciation variation on a subword level and thus improves robustness against false positives. Recall is improved by 6% absolute when retrieving on the merged search space rather than using an exact lattice search. By modeling subword pronunciation variation, we increase recall in a high-precision setting by 2% absolute compared to the edit-distance method.

Full Paper

Bibliographic reference.  Mertens, Timo / Schneider, Daniel / Köhler, Joachim (2009): "Merging search spaces for subword spoken term detection", In INTERSPEECH-2009, 2127-2130.