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If you've ever felt like Facebook or any other app on your phone was listening to your conversations, you're not entirely wrong.

While it may seem like Facebook is listening to you, it's highly unlikely the social media network is tracking your every word through your phone's microphone. That would require Facebook to record you at all times, which is unrealistic given the sheer size of data storage that would require, Antonio Garcia Martinez, a former Facebook employee, wrote in an op-ed for Wired in November.

"Constant audio surveillance would produce about 33 times more data daily than Facebook currently consumes," he explained. "The harsh truth is that Facebook doesn’t need to perform technical miracles to target you via weak signals. It’s got much better ways to do so already."

A Facebook spokesperson confirmed to Money that the company doesn't use phone microphone's to "listen in on real-life conversations in order to target people with relevant ads."

"We only access your microphone if you have given our app permission and if you are actively using a specific feature that requires audio," the Facebook spokesman added. "We do not access the microphone just because the app is opened nor do we use it when you’re not in the app."

But that doesn't mean Facebook and other apps aren't listening to certain sounds around you through your phone's mic. A December report from The New York Times claims there are hundreds of smartphone games using software from a company called Alphonso that does take advantage of access to your phone's mic.

"Using a smartphone’s microphone, Alphonso’s software can detail what people watch by identifying audio signals in TV ads and shows, sometimes even matching that information with the places people visit and the movies they see," the Times explained. "The information can then be used to target ads more precisely and to try to analyze things like which ads prompted a person to go to a car dealership."

And then there are devices like Amazon's Alexa, a voice-activated smart home system in millions of homes across the world, that are literally built to listen to you — though these devices typically have a cue word like saying "Alexa" (and there are ways to turn off Alexa's microphone and delete voice recordings). Facebook was reportedly set to roll out a similar product soon that had video chat and digital assistant capabilities, but the company postponed its release amid the ongoing data privacy scandal with Cambridge Analytica, Bloomberg reported.

So how do companies use your phone's microphone to collect data?

During a meeting with the members of the House of commons earlier this week Cambridge Analytica whistleblower Christopher Wylie, a former employee at the U.K. political firm, explained how companies collect data on users. "It's not to say that all audio has to be somebody speaking," Wylie told the members of parliament. "There's audio that can be useful in terms of, are you in an office environment? Are you outside? Are you watching TV? What are you doing right now?"

Those environmental sounds — the ambient noises around you — help companies target advertisements based on where you are at that moment, Wylie said. He noted he could not say for certain that Facebook was engaging in this practice, but it is a tactic used by companies generally. (And he dodged a direct question about whether Facebook was listening to users through their microphones, saying that was a question for the social media network.)

So what if you want to block Facebook or another app's access to your mic? It's pretty simple.

How to turn off app's access to your microphone on an iPhone

On iPhones with iOS11 or higher, go to Settings —> Privacy —> Microphone and then swipe to turn off any app's access to your microphone.

How to turn off app's access to your microphone on an Android

For Android phones operating on Oreo 8.0 or higher, open your smartphone Settings —> Apps & Notifications —> App Info —> App Permission. From there, you can revoke an app's access to your phone's microphone.