Some smartphone games are listening to what your mic picks up — but not to hear what you say. Instead, they’re trying to hear what you’re watching.

This is something smartphone apps have been doing for a little while now: using microphone access to tell what shows you watch, which ads you hear, and even what movies you see. But a report in The New York Times last week shows the practice may be more prevalent — and more secretive — than consumers might like.

The Times says that it identified more than 250 games on the Google Play Store that include just one specific type of software for monitoring users’ TV habits. It’s from a company known as Alphonso, and the apps that include it — the ones that disclose it, at least — often don’t make what they’re doing particularly clear. Most apps seem to hide their disclosure in their description, beneath a “read more” button.

If you miss that initial warning, you might not know what you’re getting into once you open the app. One game we installed, Endless 9*9 puzzle by Imobile Game Studios, immediately asked for location and microphone access, without explanation. The app did disclose that it was tracking “TV viewership details” in order to “show you TV-related content and ads,” but only if you went into the game’s settings. Users didn’t have to proactively agree.

As the Times points out, the Federal Trade Commission has warned companies about this behaviour in the past. In 2016, it told a dozen Android app developers using similar software, called SilverPush, that users need to be notified of what type of information their apps are collecting and why it’s being collected.

Those apps weren’t warning users at all about data collection, whereas the apps identified by the Times are presenting that information, even if it’s hidden. It’s not clear if that goes far enough though, and prior FTC guidance suggests it might not. The commission has said that only including disclosures in, say, a YouTube video description isn’t acceptable, since not every viewer may see it. Since people can download these games without viewing the disclosure, the same issues could come up here.

The Times says that some of these apps continue to monitor a phone’s microphone even after they’re closed. And while most apps appeared to be on Android, it reports that some were on Apple’s App Store as well. Both Apple and Google require apps to request microphone access — so users do have to grant permission before an app can start listening — but it isn’t always clear beforehand that the app will still work even without that authority.

There have been conspiracy theories for years now about major apps — Facebook, in particular — tapping smartphone mics in order to listen to what people say and then displaying ads based on their conversations. That isn’t quite what’s happening here; though these apps can hear everything you say, they’re only supposed to listen for recognizable audio from TV shows, movies, and advertisements, which they then use for ad targeting. That doesn’t make the behaviour any more welcome, but it is at least slightly less creepy.

And as for Facebook, it doesn’t need to listen to you. It has a ton of data already by tracking what you’re doing on its website, in its apps, and even on other sites and apps that serve its ads.