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The US Federal Trade Commission slapped a record $170 million fine on YouTube earlier this week for violating online privacy laws for children. That may be just the beginning. Regulators hinted that voice assistants like the Google Assistant or Amazon's Alexa could be their next target.

On Wednesday, the FTC and New York Attorney General Letitia James said that YouTube, owned by Google, knowingly and illegally collected children's data without their parents' consent. The practice ran afoul of the federal Children's Online Privacy Protection Act, or COPPA.

YouTube, which welcomes more than 2 billion visitors a month, is the world's largest video site, with more than 500 hours of video uploaded to the platform every minute. You technically have to be 13 or older to use the site, but kids and parents have long ignored that rule. In response to the fine, Google said it would make sweeping changes to YouTube, including having creators clearly identify their child-focused content and ending targeted ads for those videos.

Children are highly vulnerable internet users. Ashley Boyd, vice president of advocacy, Mozilla

The fine is just the latest example of regulators taking a more critical stand against big tech, which has gotten into hot water for its failure to protect our data. One of the most surprising aftereffects of the YouTube case, though, will be a harder look at the world of voice searches -- an area that's already created a lot of controversy.

"Another issue that we are planning to look at is the collection and use of audio files," Andrew Smith, director of the FTC's Bureau of Consumer Protection, said during a press conference Wednesday after the fine was announced.

Smith said the agency already has policies regarding voice commands, such as those a child would give to an internet-connected toy. It's fine for devices to record the voice queries of children without parental consent, but only if the files are deleted "as soon as practicable afterwards," Smith said. The FTC addressed children's voice recordings in depth two years ago when it released a new policy enforcement statement for COPPA.

Some in the tech world praised the move.

"Children are highly vulnerable internet users: They can't decipher privacy policies, can't meaningfully consent to what data they share, and are impressionable to targeted advertisements," Ashley Boyd, Mozilla's vice president of advocacy, said in a statement Thursday. "Any extra attention paid to online privacy is a good thing -- especially in the realm of voice, and especially in the context of kids."

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At the press conference, Smith didn't mention any tech giants by name, and the FTC didn't respond to a request for additional comment about its review of voice commands. But when you think of voice technology, no products have had as much influence as Amazon's Alexa, Google's Assistant and Apple's Siri. All those services have apps and content aimed at kids, including the ability to have the software tell you G-rated jokes. Alexa and the Google Assistant have a setting where commands must be followed by the word "please," aimed at teaching children good manners. Amazon also has an Echo Dot Kids Edition, which comes in bright colors and includes a kid-friendly version of Alexa.

An FTC investigation into these leading voice assistants would add even more heat to tech companies already under intense government scrutiny, facing questions over their potential monopolistic practices and privacy breaches. Voice assistants have also become big businesses for Google and Amazon, and any regulatory changes could have noticeable impacts on how their smart speakers will interact with customers.

Google didn't respond to multiple requests for comment. Amazon declined to comment.

Jeff Chester, of the Center for Digital Democracy, said it makes sense for the FTC to scrutinize Google in areas other than online video. "Everything is connected at Google," Chester said. "The commission failed to look at Google's child-directed actions throughout its entire operation."

Chester's organization, along with a group called the Campaign for a Commercial-Free Childhood, also led a cohort of children's development groups by filing a complaint in May with the FTC, urging the agency to investigate the Echo Dot Kids Edition.

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However, Chester and other child advocates are worried about the damage that could be done by reviewing the COPPA rules. He thinks tech giants could take advantage of the reassessment by trying to weaken the restrictions.

Even though the FTC has addressed voice recordings in its enforcement policies, the commission said during its press conference that it could possibly change the COPPA rule itself to address voice recordings, too. But Angela Campbell, the lawyer who drafted the complaint against YouTube to the FTC, is also worried about changing the rule. She said it's "unnecessary."

"By putting it in the rule, they open the door to potential abuses," said Campbell, co-director of Georgetown University's Institute for Public Representation. "I worry if you loosen that up, you intentionally or unintentionally create additional loopholes. Whatever inch you give [the tech companies], they're going to take a mile."

Already controversial

Google, Amazon and Apple have already faced blowback for privacy concerns when it comes to audio recordings of digital assistant searches.

In July, Google confirmed that third-party workers who analyze language data from the Assistant leaked private Dutch conversations. Belgian public broadcaster VRT NWS said more than 1,000 files had been leaked, including recordings from instances where users accidentally triggered Google's software.

Amazon has said an "extremely small" number of Alexa recordings are annotated to help make its speech recognition systems better. Apple contractors reportedly hear private recordings too, including medical information, according to a report in July from The Guardian. Apple told The Guardian a "small portion" of the data is used to help improve Siri and dictation.

In response to the scandals, Google and Apple paused their language review processes for voice recordings. Apple soon after decided to listen to recordings only from users who opted in to its human review program. Amazon began letting users opt out of human review.

Amazon in particular has drawn criticism for voice recordings of children. Two lawsuits in June alleged that Amazon failed to get proper consent before recording children's voices and storing those recordings indefinitely. And Mozilla, the nonprofit tech company that owns Firefox, last year called on Amazon to provide more-specific information on how it uses children's data collected through the Echo Dot Kids Edition.

Amazon has said its kids-focused Echo Dot and its related FreeTime on Alexa software are COPPA-compliant. It mentioned in a blog post published in May that it requires parental consent and allows parents to delete children's profiles and recordings. But some critics don't think those protections are enough.

In the meantime, while Chester thinks the YouTube settlement with the FTC could've been for a larger amount, he considers it a big win for COPPA. "It opens the door for more advocacy," he said. "It continues the fight."