Patent ID: 7165031

Claim:
A speech recognition apparatus operable to determine a confidence score indicative of the probability that an utterance has been correctly matched to a word, said apparatus comprising: a receiver operable to receive a signal indicative of an utterance; a matching unit operable to determine, for each of a plurality of word models, a match value indicative of the closeness of match of each said word model to a said signal received by said receiver; a calculation unit operable to calculate an exponential of a constant multiplied by a match value determined by said matching unit for an estimate of the likelihood of the signal matching a word model given that said signal is indicative of an utterance corresponding to a word represented by said word model; and a processing unit operable to process estimates generated by said calculation unit to determine a confidence score indicative of the probability that an utterance has been correctly matched to a word by calculating a fraction, the numerator of which comprises the estimate generated by said calculation unit from a match value for a word model for said word and the denominator of which comprises a sum of estimates generated by said calculation unit from match scores for a plurality of word models.