Although it is estimated that around half of all new laptops have a built-in fingerprint reader, the use of biometric technologies for authentication still tends to be confined to airports and border controls.

There is, however, one area of biometrics that could be ideal for many applications, and which, its proponents say, has reached a high level of reliability: voice recognition.

Voice recognition has a big advantage over most other biometric technologies in that users can enrol themselves over the telephone rather than have to attend in person to deliver a fingerprint or an iris scan. The technology also requires no special reader, other than a microphone.

... The biggest challenge for using voice recognition technology to authenticate a user logging in to a network is the poor quality of the microphone in most PCs, ...

He warned, however, that although the technology is now robust and able to cope with difficult environments, such as background noise, there will always be a small percentage of instances where the system will fail to recognise a voice properly.

http://searchsecurity.techtarget.co.uk/news/article/0,289142,sid180_gci1368621,00.html