7. A method for verifying an identity of a speaker, comprising: receiving feature vectors extracted from an utterance received from a microphone and made by a speaker claiming an identity; measuring dissimilarity between the feature vectors and a codebook associated with a version of the utterance known to be made by the identity; analyzing the utterance to ascertain information about repeating occurrences of the feature vectors in the utterance; comparing the information about repeating occurrences of feature vectors occurring in the utterance with information about repeating occurrences of feature vectors in a version of the utterance known to be made by the claimed identity; assigning a penalty to the measured dissimilarity based on the comparison; and determining whether to accept the speaker as the identity using the measured dissimilarity modified by the assigned penalty, wherein the assigned penalty comprises a penalty for each of the feature vectors of the utterance, wherein the assigned penalty for each feature vector is based on a difference between a number of repeating occurrences of the respective feature vector of the utterance and a number of repeating occurrences of the corresponding feature vector of the version of the utterance know to be made by the identity.
7. A method for verifying an identity of a speaker, comprising: receiving feature vectors extracted from an utterance received from a microphone and made by a speaker claiming an identity; measuring dissimilarity between the feature vectors and a codebook associated with a version of the utterance known to be made by the identity; analyzing the utterance to ascertain information about repeating occurrences of the feature vectors in the utterance; comparing the information about repeating occurrences of feature vectors occurring in the utterance with information about repeating occurrences of feature vectors in a version of the utterance known to be made by the claimed identity; assigning a penalty to the measured dissimilarity based on the comparison; and determining whether to accept the speaker as the identity using the measured dissimilarity modified by the assigned penalty, wherein the assigned penalty comprises a penalty for each of the feature vectors of the utterance, wherein the assigned penalty for each feature vector is based on a difference between a number of repeating occurrences of the respective feature vector of the utterance and a number of repeating occurrences of the corresponding feature vector of the version of the utterance know to be made by the identity. 8. The method of claim 7 , wherein the assigned penalty for a given feature vector is reduced if the difference between the number of repeating occurrences of the respective feature vector of the utterance and the number of repeating occurrences of the corresponding feature vector of the version of the utterance know to be made by the identity is determined to be less than a predefined value.