Editor's pick: Originally published June 24.

Companies are combating sophisticated hackers by utilizing voice biometrics to authenticate customers when they call banks or credit card companies, adding another layer of security to prevent a growing amount of fraud.

As customers find it increasingly vexing to provide not only their username and password and other personal details, companies must balance combatting fraud with providing a less cumbersome experience. A growing number of companies are adopting voice biometrics, where voice and speech patterns are used to identify the individual calling with questions about their account balance or transaction.

"When you contact financial institutions, you already have a problem and you want that issue resolved quickly," said Erica Thomson, a real-time authentication consultant at NICE, a Ra'anana, Israel-based software solutions provider.

Providing your mother's maiden last name or the nickname for your first dog is becoming an obsolete strategy since cyber attackers have already mined social media for the seemingly private information. Thwarting hackers requires staying one step ahead of them.

Voice biometrics is being implemented by many financial institutions such as banks and retirement providers, because it does not require consumers to be physically present or have the software capable of authenticating them through their fingerprint or an iris scan. The technology encompasses an individual's voiceprint of over 100 vocal and personal characteristics with 50% consisting of their physical traits such as their vocal cords, sinuses and lung capacity and the remaining half comprising of their personal tone, pitch and pace when they speak, she said.

Many companies utilize the technology by acquiring a person's voiceprint passively or simply capturing it as the individual inquires about a transaction and answers questions with a customer service representative. The next time they call to ask about a purchase or a deposit, the company can compare their current voice against the voiceprint, Thomson said. Within seconds, the employee at the bank can determine if the caller's voice matches the voiceprint.

"We've made life easy for fraudsters with social media for many years," she said. "This technology aids financial institutions so they can help their customers quicker and sort out their situations faster."

After a pilot program last year, Citigroup now authenticates a small fraction of its customers who have their branded credit cards by using NICE's voice biometrics technology. As of June, 750,000 customers out of a total of 23.8 million active and inactive accounts can access their accounts by using their voiceprint.

"This is very critical for our customers because it increases their protection," said Andrew Keen, a director in the consumer banking unit at Citigroup. "We are putting the onus on them to prove who they are now."

The feedback from consumers has been positive and Citigroup is still determining whether to use the software for its banking customers.

"Within the first 15 seconds of a customer calling, they are fully authenticated, because it all happens when you tell us why you called," he said. 

How Voice Biometrics Works

Fraudsters have always remained one step ahead and have attempted to circumvent voiceprints by calling unsuspecting consumers and pretending they are from technical support or seeking answers for a survey to record their voices, said Thomson. The hackers want to trick unwary people into saying certain phrases or words and splicing them into new recordings.

The cyber criminals have failed, because this method is "not applicable to real authentications" and they are not fluid conversations, she said. Voice biometrics does not authenticate people by particular words and phrases, so these attempts at phishing are not successful.

"There is no technology today that can make me sound like you," Thomson said.

Voice biometrics operates by judging characteristics such as the pitch and tone of how a person speaks and since consumers will say different things each time they call their bank, simply recording someone's voice is not feasible.

"It is impossible to recreate that voice, and it can not be engineered," she said. "There are not any mandatory questions, so the technology maintains the integrity and uniqueness of that person's voice."

The biometric system uses "sophisticated algorithms" to match comments made by that person against their previously recorded voiceprints to verify their identity, said Amit Basu, a professor of management information system at the Cox School of Business at Southern Methodist University in Dallas.

The voiceprint utilized by companies are encrypted and only contains a "registry of their characteristics, not the conversation," Thomson said. The technology does not require storing any customer information such as a recording of their voice or social security numbers, increasing security and lowering the odds of fraud occurring.

Computers can capture the uniqueness of each voice and convert the "analog sound waves into a sort of voiceprint or binary image of the sound that your voice makes and various algorithms build this unique 'image' or a biometric vector of your voice," said Jason Braverman, CIO of Hoyos Labs, a New York-based mobile biometric authentication company.

Will Voiceprint Replace Other Biometrics?

Combining voiceprint with other biometrics such as fingerprint or iris scans will be the most effective approach rather than using it to replace other authentication methods, said Basu.

One advantage is when hackers attempt to replicate a person's voice, that voiceprint is also retained and left behind for comparison. The likelihood that the system mistakenly matches a person's voice is low.

"Overall, there is more chance of false rejection than false acceptance," he said.

In some instances, voice biometrics can completely replace the use of a username and password as long as people enroll again, because voices tend to change with age and weight gains or losses, said Braverman.

Voice biometrics can replace the traditional method of verifying a person for basic account inquires such as when a bill is due. The use of voice biometrics will be an "added layer of authentication" for transactions which pose a higher risk of fraud such as transferring money into another account, said Steve Williams, a vice president of business strategy at Verint Systems, a Melville, N.Y.-based software company.

Drawbacks of Voice Biometrics

Noisy environments can hamper the use of the technology but remains a minor issue as both software with smartphones and voice biometrics can minimize or remove background noise, said Thomson.

One of the downside of biometrics is that it can not be changed easily, said Jason Glassberg, co-founder of Casaba Security, a Redmond, Wash.-based cybersecurity and white hat hacking firm. 

"The true security will depend on the level of sophistication used to match highly precise and detailed voice patterns and guard against pre-recorded sounds," he said. "Nothing is ever 100% safe and even biometric data can be stolen or imitated."

Voice biometrics is not the only solution to preventing hackers from obtaining data, because fraudsters will develop more refined methods, said Thomson.

"Cyber criminals will attempt to enter a network through other channels," she said. "This is what happens with all technology - the fraudsters become more sophisticated. We are always developing solutions to stay ahead of them."