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dc.contributor.authorAbberley, Daveen
dc.contributor.authorKirby, Daviden
dc.contributor.authorRenals, Steveen
dc.contributor.authorRobinson, Tonyen
dc.date.accessioned2006-05-26T16:23:49Z
dc.date.available2006-05-26T16:23:49Z
dc.date.issued1999
dc.identifier.citationIn Proc. ESCA Workshop on Accessing Information In Spoken Audio, pages 19-24, Cambridge, 1999.
dc.identifier.urihttp://homepages.inf.ed.ac.uk/srenals/pubs/1999/esca99-thisl/
dc.identifier.urihttp://hdl.handle.net/1842/1193
dc.description.abstractIn this paper we introduce a set of related confidence measures for large vocabulary continuous speech recognition (LVCSR) based on local phone posterior probability estimates output by an acceptor HMM acoustic model. In addition to their computational efficiency, these confidence measures are attractive as they may be applied at the state-, phone-, word- or utterance-levels, potentially enabling discrimination between different causes of low confidence recognizer output, such as unclear acoustics or mismatched pronunciation models. We have evaluated these confidence measures for utterance verification using a number of different metrics. Experiments reveal several trends in `profitability of rejection', as measured by the unconditional error rate of a hypothesis test. These trends suggest that crude pronunciation models can mask the relatively subtle reductions in confidence caused by out-of-vocabulary (OOV) words and disfluencies, but not the gross model mismatches elicited by non-speech sounds. The observation that a purely acoustic confidence measure can provide improved performance over a measure based upon both acoustic and language model information for data drawn from the Broadcast News corpus, but not for data drawn from the North American Business News corpus suggests that the quality of model fit offered by a trigram language model is reduced for Broadcast News data. We also argue that acoustic confidence measures may be used to inform the search for improved pronunciation models.en
dc.format.extent48491 bytesen
dc.format.extent62511 bytesen
dc.format.mimetypeapplication/octet-streamen
dc.format.mimetypeapplication/pdfen
dc.language.isoen
dc.titleThe THISL broadcast news retrieval system.en
dc.typeConference Paperen


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