Summary: A PHONE­DEPENDENT CONFIDENCE MEASURE FOR UTTERANCE REJECTION
Ze'ev Rivlin, Michael Cohen, Victor Abrash, and Thomas Chung
Speech Technology and Research Laboratory
SRI International
Menlo Park, California 94025
zev@speech.sri.com
ABSTRACT
An acoustic confidence measure for acceptance/rejection
of recognition hypotheses for continuous speech utterances
is proposed. This measure is useful for rejecting utterances
that are out of domain, or contain out­of­vocabulary words
or speech disfluencies. A phone­based approach is imple­
mented so that a single global threshold can be applied to
hypothesis rejection for any word sequence. Phone confi­
dence is computed for each frame of speech as the posterior
phone probability given the acoustic observation. Word se­
quence confidence is evaluated as the average phone confi­
dence, either by weighting all frames equally or by normal­
izing by phone duration. The confidence measure is tested
on a database of spoken company names. When normal­

Source: Abrash, Victor - Speech Technology & Research Laboratory, SRI International

Collections: Computer Technologies and Information Sciences