Patent ID: 7617101

Claim:
A method for utterance verification implemented in a computer system having a feature vector extraction module, a speech recognition module, a speech segmentation module, a verification feature vector generation module, a verification score calculation module, a verification score combination module, and a decision module, the method comprising the steps of: (A) extracting a sequence of feature vectors from an input speech by the feature vector extraction module; (B) inputting the sequence of feature vectors to the speech recognition module for obtaining at least one candidate string; (C) segmenting the input speech into at least one speech segment by the speech segmentation module according to the content of candidate string, which comprises individual recognition units, wherein each speech segment corresponds to a recognition unit and each recognition unit corresponds to a verification unit; (D) generating a sequence of verification feature vectors for each speech segment by the verification feature vector generation module according to the sequence of feature vectors of the speech segment, wherein the verification feature vectors are generated by normalizing the feature vectors using the normalization parameters of the verification unit corresponding to the speech segment, the normalization parameters of the verification unit are the means and the standard deviations of the feature vectors corresponding to the verification unit in training data, and these parameters are calculated in advance of runtime; (E) utilizing a verification-unit corresponded classifier for each speech segment to calculate the verification score by the verification score calculation module, where the sequence of verification feature vectors of the speech segment is used as the input of the classifier, wherein said classifier is a neural network and the neural network is an MLP (multi-layer perceptron), wherein the MLP is used to calculate the verification score by inputting the verification feature vector and performing a feed-forward operation, and wherein the verification score of a speech segment is the mean of the verification scores of the sequence of verification feature vectors corresponding to the speech segment; (F) combining the verification scores of all speech segments for obtaining an utterance verification score of the candidate string by the verification score combination module; and (G) comparing the utterance verification score of the candidate string with a predetermined threshold by the decision module so as to accept the candidate string if the utterance verification score is larger than the predetermined threshold.