On Tuesday, Facebook's Mark Zuckerberg took hours of questions from senators about his platform, in a hearing that was mostly about the Cambridge Analytica revelations, and the wider privacy concerns that have plunged the company into a major crisis of trust with the public.

Not all of the questions were on topic.

Sen. Gary Peters (D-Mich.) was one of the members of Congress who instead used a portion of his time to ask the company about other rumors and stories that are critical of the company.

In Peters's case, the question happened to refer to one of the biggest conspiracy theories that people believe about Facebook.

"I hear it all the time, including from my own staff," Peters said. "Yes or no, does Facebook use audio obtained from mobile devices to enrich personal information about its users?"

"No," Zuckerberg replied. He paused and then said he wanted to elaborate. "You're talking about this conspiracy theory that gets passed around, that we listen to what's going on on your microphone and we use that for ads. We don't do that."

Zuckerberg, and the tech-savvy press covering this marathon of a hearing, may have rolled their eyes at this question - the claim has, after all, already been debunked by Snopes and countless news outlets.

But among people who haven't spent years thinking about Facebook and privacy on the Internet, it might not only seem possible that Facebook is listening in on your phone calls - but believable.

There are a lot of anecdotes that propel this story around the Internet: Someone is talking on the phone and mentions they want to buy a Jeep. Hours later, a Jeep ad shows up in their News Feed.

Or maybe someone's talking to their friend, near a phone, and says they need a new blazer. They check their phone, and there's an ad for one. You might have an anecdote like this yourself. A viral video claimed to prove this with a test - the video has more than 1 million views.

The rumor has gone viral at least two other times: once, in 2014, when Facebook launched an opt-in app that could listen and identify the music or TV show in the background while you wrote a status update, and in 2016 when a professor's eerie experience was the basis of an article claiming that Facebook was listening to everything you say (it's worth noting that the professor in question later clarified that she herself made no such claim).

And these stories can often be very convincing. The podcast Reply All recently devoted an entire episode to debunking this idea and then trying to convince people who were sure it happened to them that there might be another explanation to that ad that freaked them out.

As many journalists - and even some former Facebook employees - have pointed out, Facebook doesn't really need to be listening in on your phone calls to target ads and put things in your News Feed that are eerily on target.

"Facebook can find you on whatever device you've ever checked Facebook on.

"It can exploit everything that retailers know about you, and even sometimes track your in-store, cash-only purchases; that loyalty discount card is tied to a phone number or email for a reason," wrote Antonio García Martínez in Wired. Martínez was Facebook's first ads targeting product manager.

Among other things, your location information, your purchase history, and your web activity could have contributed to Facebook's creepy ability to show you ads that seem to read your mind.

It's worth noting that Facebook also recently announced it would limit how companies could use third-party data like purchase history to target ads - although advertisers could still work with third-party data brokers to get that information outside Facebook.

In 2016, Facebook released a longer statement about this rumor. Here it is, in full:

Facebook does not use your phone's microphone to inform ads or to change what you see in News Feed. Some recent articles have suggested that we must be listening to people's conversations in order to show them relevant ads.

This is not true. We show ads based on people's interests and other profile information - not what you're talking out loud about.

We only access your microphone if you have given our app permission and if you are actively using a specific feature that requires audio.

This might include recording a video or using an optional feature we introduced two years ago to include music or other audio in your status updates.

The explanation that Facebook isn't spying on you through your microphone because it already pretty much gets the information it needs hasn't convinced many of those who believe they've experienced this phenomenon first hand.

And it's not exactly the most soothing of debunkings.

If you're worried about this, you can always go into Facebook's app permissions on your mobile device and delete its access to your microphone. Or, you know, quit.

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This article was originally published by The Washington Post.