What is a Voice Biometric?
In its simplest form, a Voice Biometric is the unique representation of the characteristics that make up an individual's voice.
Similar to a fingerprint where the various ridges, troughs and curves on a finger provide a distinct method of identification, the differing physical components of a human throat and mouth produce a unique sound which can be analysed, measured and stored. This is known as a voice print.
To produce a sound, air from the lungs is typically passed through one or more resonators such as the larynx, the oral cavity (your mouth) or the nasal cavity (your nose). The form, volume and tone of the sound varies depending on the size of the airstream, its passage out of your body and the obstructions the stream faces as it leaves. These obstructions include your tongue, gums, teeth and lips and their size and position can all affect the sound produced.
Whereas a fingerprint has approximately 40 unique characteristics, a voice has over 100 separate characteristics. This means that Voice Biometrics can be used as a very secure way of identifying and verifying an individual using nothing more than a telephone or a microphone.
To use a Voice Biometric as a means of identification, a sample of speech is analysed as part of an enrolment process. A variety of measurements are made on the sample and the results entered into a complex algorithm. The output from this algorithm is then encrypted and securely stored (it is a common misconception that the speech sample itself is stored). To verify an identity, a second sample of speech is analysed and the measurement process is repeated. If the result of the calculation matches the result obtained during the enrolment then the identity can be verified.
To ensure that the second sample is not a recording of someone's voice, a further step can be added to the verification process. This is called a liveliness test where the caller is asked to repeat a random phrase or sequence of numbers. If the voice had been recorded, it would be very hard to repeat this accurately and therefore the test would fail.
Voice Biometrics are a secure and unobtrusive way of verifying identities. They do not require any unusual behaviour during either the enrolment or verification stages - speaking is a natural process and we do it every day. The next time you are asked to provide a PIN, password or your mother's maiden name as a form of identification, think about how easy it would be for someone obtain this information (especially someone who knows you) and then think about how hard it would be to obtain your voice print.
Did You Know?
In a recent study, 33% of those asked found PINs to be especially vulnerable as an identity process because typically, information used for PINs is easy to guess.