Looking for His glorious appearing! Titus 2:13

The rapid deployment by governments and businesses of voiceprint technology – used to identify people from their speech – has aroused the concern of privacy groups who see it as a possible next frontline in the battle against overweening public surveillance.

A survey by the Associated Press of voice biometrics, the spoken equivalent of fingerprints, has found that the technology is already widely used. The AP estimated that more than 65 million voiceprints have been stored in corporate and government databases around the world.

The huge scale of take-up of the technology has surprised experts in digital surveillance. “This suggests there is a major new biometric tool that is being rolled out with very little public discussion,” said Jay Stanley, an expert on technology-related privacy issues at the American Civil Liberties Union.

He added that use of voiceprints by companies to counter fraud had its benefits, but that it came with costs. “Obviously fraud protection is a good thing, but it raises implications that need to be looked into.”

Among those implications is the potential that anonymity in speech could be threatened. Several phone services rely on guaranteeing privacy to callers – crime hotlines run by police, counselling services, and numbers that people who have suffered domestic violence or other abuse are encouraged to call in the knowledge that their identities will not be compromised, for instance.

Stanley said that if public confidence in such services were compromised, “We could lose a major avenue of anonymous speech.”

Lee Tien, senior staff attorney with the Electronic Frontier Foundation, said that voice biometrics could be used to pinpoint the location of individuals. There is already discussion about placing voice sensors in public spaces, and Tien said that multiple sensors could be triangulated to identify individuals and specify their location within very small areas.

“Even where the technology wasn’t designed for eavesdropping or tracking people, it could still identify them and associate them with a location,” he said.

The AP survey found that a number of big financial and other companies have already taken up voice biometrics with enthusiasm. An executive for Barclays said “the general feeling is that voice biometrics will be the de facto standard in the next two or three years”.

Several governments, led by Turkey where the mobile phone company Turkcell has stored voiceprints of 10 million people, have also leapt on the bandwagon.

For companies, the big attraction of voiceprints is to be able to follow consumers as they move from one store or part of a store to another, and between commercial channels. Professor Joseph Turow, a privacy and surveillance expert at the University of Pennsylvania, said that as a result individual citizens were increasingly losing control over their own identities.

“Companies are using data drawn from our internet and purchasing behaviour – and now our voices – and connecting it to the identities that they’ve created for us. Then they can lead us in a variety of different directions, based on their stereotype of us,” he said.

Amid this fast-developing data world, there is always the risk that the technology is not as precise as suggested, leading to mistakes. “Biometrics are never 100% accurate,” said Stanley. “Are people going to be blacklisted by government institutions because their voice is mistaken for that of a fraudster?”