| 摘要 |
A method of voice authentication comprises enrolment and authentication stages. During enrolment, a user is prompted to provide a spoken response which is recorded using a microphone (5). The recorded signal is divided into frames and converted into feature vectors. Feature vectors are concatenated to form featuregrams. Endpoints of speech may be determined using either explicit endpointing based on analysis of energy of the timeslices or using dynamic time warping methods. Featuregrams corresponding to speech are generated and averaged together to produce a speech featuregram archetype. During an authentication stage, a user is prompted to provide a spoken response to the prompt from which a speech featuregram is obtained. The speech featuregram obtained during authentication is compared with the speech featuregram archetype and is scored. The score is evaluated to determined whether the user is a valid user or an impostor. Accordingly, a method of gain control for optimising input voice is used. If the amplified input signal is higher/lower than a predetermined limit, the gain is lowered/raised so there is no increase in gain between signals. To stop replay attacks, a method comprises prompting the user for a plurality of responses, and checking the responses to see if they are substantially identical. A smart card to perform the above voice authentication is possible.
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