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Evaluation of an automatic speaker-verification system over telephone lines

An automatic speaker-verification system accessed by test customers from their own telephones over dialed-up lines has been evaluated. The test population consisted of over 100 male and female speakers who called up nominally once each working day over a period of five months. The operation of the system is based on a set of functions of time obtained from acoustic analysis of a fixed, sentence-long utterance. These functions are compared with stored reference functions to determine whether to accept or reject an identity claim. The system is implemented on a NOVA 800 laboratory computer. Telephone line access to the computer is via a data set hookup. Identity claims are made by keying an identification number on a Touch-Tone® dial. Instructions and responses to the customer are made by means of a programmed voice-response system. Reference data was computed off-line and updated with the analysis data of accepted utterances. The evaluation indicated an error rate of approximately 10 percent for new customers and approximately 5 percent for adapted customers.