Patent ID: 7464031

Claim:
A speech recognition system, comprising: a features extractor that extracts a multitude of speech features directly from input speech; a log-linear function that receives the multitude of speech features obtained from the input speech and determines a posterior probability of each of a plurality of hypothesized linguistic units given the extracted multitude of speech features by applying the formula: P ⁡ ( H j | features ) = P ⁡ ( w 1 k | o 1 T ) = ∏ i = 1 k ⁢ ⁢ P ⁡ ( w i | w 1 i - 1 , o 1 T ) , where: H j is a jth hypothesis that contains a sequence of word (or other linguist unit) sequence w 1 k =w1w2 . . . wk i is an index pointing to the ith word (or unit) k is a number of words (units) in the hypothesis T is a length of the speech signal w 1 k is a sequence of words associated with the hypothesis H j , and o 1 T is a sequence of acoustic observations, with conditional probabilities represented by a maximum entropy log-linear model: P ⁡ ( w i | w 1 i - 1 , o 1 T ) = ⅇ ∑ j ⁢ λ j ⁢ f j ⁡ ( w i , w 1 i - 1 , o 1 T ) Z ⁡ ( w 1 i - 1 , o 1 T ) , where: λ 1 are parameters of the log-linear model, f 1 are a multitude of features extracted, and Z is a normalization factor that ensures that Equation 2 is a true probability (will sum up to 1); and a search device that analyzes the posterior probabilities determined by the log-linear function to determine a recognized output of unknown utterances.