Hey, Siri: Are we paranoid, or are you eavesdropping on us to serve us advertising?
Have you ever had a conversation about unicorns, then unicorn ads started popping up in your Facebook feed?
If it hasn't happened to you, it's likely happened to someone you know.
Some experiences of people's phones seeming to eavesdrop then target advertising include parachuting, Harry Potter merchandise and IKEA furniture.
Facebook says no way
Some have suggested Facebook is listening to conversations to show users relevant ads.
Facebook issued a statement in 2016 denying the claim.
"Facebook does not use your phone's microphone to inform ads or to change what you see in News Feed," it reads.
Rather, they "show ads based on people's interests and other profile information—not what you're talking out loud about."
Facebook's former marketing vice president also denied it on Twitter, but curiously, the tweet has since been deleted.
Is Facebook lying to us (as they have been accused of in the past) or are phones really eavesdropping on us?
Researchers at Northwestern University looked at 17,260 of the most popular Android apps to investigate if they were secretly recording users' conversations.
They discovered some pretty dodgy stuff (like apps taking screenshots and producing videos that were sent to third-party domains), but they didn't find any instances where a microphone was activated or audio was recorded then sent to a third party.
Their findings don't rule out eavesdropping. It might just mean the researchers didn't discover the specific way it happens.
For example, audio could be converted to text before being sent on.
Et tu, Apple?
The Northwestern researchers only looked at Android devices. What about Apple?
Apple famously let its employees listen to recordings of Siri users, including audio of people having sex.
The only way this could have happened was if Apple made and then sent audio recordings from iPhones to its servers.
A managing security consultant at NCC Group and former ECU lecturer Dr. Peter Hannay says Facebook and other apps can listen in on audio as long as users have given their permission.
He says some phones, like the iPhone, also require that the app must also be running while listening in.
Shhh, they'll hear us
Peter says that, even though Facebook denies eavesdropping, their patent filings suggest it's something they're quite interested in.
"Facebook filed [a] US Patent … in 2018 which outlines a mechanism to profile ambient audio gathered from a mobile device," Peter says.
"So while they may not currently make use of such technology, they likely have the capability to do so, both from an access and a technical capability standpoint."
And if they do, who knows? The next sticker on your webcam might be teeny tiny earmuffs on your phone.