Patent ID: 7970611

Claim:
A method for an authentication server in a digital communication network environment, the authentication server having a first database for storing at least one enrollment voice characterizing parameter set, each enrollment voice characterizing parameter set being associated with one subscriber enrolled in the authentication server, being derived from at least one enrollment utterance spoken by said one subscriber during an enrollment process and being associated with at least one enrollment process condition indicating a process condition during the enrollment process, and a second database for storing correction parameters for correcting a voice characterizing parameter set based upon mismatch between at least one enrollment process condition and at least one test process condition, the method comprising the steps of: receiving a coded speech signal over a network channel of digital communication network, the speech signal resulting from at least one spoken test utterance of a claimant claiming to be a certain subscriber enrolled in the authentication server, and decoding the coded speech signal; determining at least one test process condition indicating a process condition having influenced the speech signal, wherein the at least one process condition comprises at least one network channel property of the digital communication network during a transmission of the coded speech signal; determining a test voice characterizing parameter set from the decoded speech signal; comparing the determined at least one test process condition with the at least one enrollment process condition associated with the stored enrollment voice characterizing parameter set of the certain subscriber the claimant claims to be; and when the comparing step results in a mismatch between the at least one test process condition and the at least one enrollment process condition, compensating effects of said mismatch by correcting the determined test voice characterizing parameter set or the stored enrollment voice characterizing parameter set with the corresponding correction parameters stored in the second database and that correct for the mismatch between the at least one test process condition and the at least one enrollment process condition.