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An Introduction to Biometrics - Voice Recognition

What is voice recognition?
Voice recognition technology is a means of using the unique characteristics of a person’s voice including the rhythm of their vocal cords and the concavity of their mouth to create a “voice print” which is then used for identification purposes.

How does it work?

The first step in voice recognition is for an individual to produce an actual voice sample. The unique patterns of an individual’s voice is produced by the vocal tract. It is these unique patterns which is used by voice recognition systems. Even though people may sound alike to the human ear, everybody, to some degree, has a different or unique annunciation in their speech.

To ensure a good quality voice sample, the individual usually recites some sort of text, which can either be a verbal phrase or a series of numbers. The individual usually has to repeat this a number of times. The most common devices used to capture an individual’s voice samples are computer microphones, mobile phones, and land line based telephones. Finally, the voice samples are converted from an analog format to a digital format for processing.

The next steps are unique feature extraction and creation of the template. The extraction algorithms look for unique patterns in the individual’s voice samples. To create the template, a “model” of the voice is created. In voice recognition systems, stochastic models, particularly Hidden Markov models, have been utilized. With this type of modeling, statistical profiles are created by comparing various voice samples to determine any repeating patterns.

The final step is verification of the individual. At this stage, the live voice sample submitted for verification is compared to the statistical profiles created, and a probability score is then computed which describes the likelihood that the individual is who he or she claims to be.


The current applications for voice recognition systems are for physical access entry and where “remote identity verification” is required. Examples of this include call center automation, and transaction processing applications via the telephone or computer. Popular applications in this area are financial transactions (account access; funds transfer; bill payment; trading of financial instruments) and credit card processing (address changes; balance transfers; loss prevention). Voice recognition has also made an impact in the penal system. This technology has been used for inmates on parole, juvenile inmates, and those under house arrest.


Further information


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