Speech-recognition software is used today by banks and other institutions to conduct customer transactions over the phone without the need for a live customer-service representative. But such systems recognize mainly numbers and words, not individual voices. If you utter the right PIN and account number, you get through.

Now a system being readied for commercialization in Europe treats an individual’s voice as the gate-opener. That capability would add another security layer: while your PIN can be compromised, your voice is not so easily stolen. It could also eliminate the need to remember and recite account numbers and PINs.

Owned by Surrey, U.K.-based Biometric Security, the system, called Voice Vault, requires users simply to utter their name, birth date, and a password, says chief technology officer Vance Harris. The company, like others in the field, already has a handful of banks as clients, who use “voiceprinting” for internal security purposes. But Voice Vault’s system will be made available to general account holders at an undisclosed European bank by December, says Harris.

The system will require a user to remember a minimal amount information, while relying instead on that person’s voice for authentication. First, customers “register” their voices in a training session that involves saying words designed to capture the frequencies associated with their voice. The system then constructs a statistical model that predicts what a speech waveform would look like when the person is uttering an entirely novel sentence.

Then, when that person’s account is accessed over a phone, the system not only confirms that the articulated name, birthdate, and password are accurate, but also checks to see if the waveforms of those utterances match the template stored with the account.

Such modelling of the vocal tract is a popular approach these days for voice verification, says Aladdin Ariyaeeinia, a voice researcher at the University of Hertfordshire, England. Indeed, many companies are developing similar systems.

Much farther in the future is so-called “text independent” identification, which would be so good at recognizing individual voices that you’d merely call your bank and say “What’s my balance?” without having to give any other information.

Voiceprints have some over other biometrics too. Ariyaeeinia notes that while some banks are now looking at using more established forms of biometrics for online banking – fingerprints and iris scans – these require additional hardware to perform the scans.

“The great advantage of voice is that all computers and phones have the sensor built in, whereas other biometrics require additional sensors,” says Mike Brookes, a signal-processing researcher at the Imperial College of Science, Technology, and Medicine in London, who specializes in voice recognition. And, he adds, voice recognition also allows you to keep your hands free.

“Voice has been on the verge of breaking through for a number of years,” says Brookes. He believes voice verification technology will finally start to take off, particularly with telecommunication and cell-phone companies, who are keen to push e-commerce services via Internet-enabled cell phones.

Another reason for the adoption of voiceprinting is the recent introduction of so-called “smart” credit and debit cards. These cards have eliminated the use of handwritten signatures for authenticating payments, and instead require customers to punch in a four-digit PIN, which is then verified against a number stored on a chip on the card.

Since the recent mass introduction of these PIN-verified cards in the U.K., for example, most types of credit-card fraud have plummeted. According to figures released in February by the U.K.’s Association for Payment Clearing Services (APACS), credit-card fraud dropped by 13 percent in 2005.

But one type of fraud continued to rise last year, by 21 percent: the problem lies in transactions made over the Internet, by phone, or by mail order. In these kinds of transactions, a card’s information can be read out or typed in without additional authentication. The field of biometrics, in general, and voiceprinting, in particular, could go a long way toward solving this problem, Harris says.