With so many modern devices containing microphones, it’s understandable that people worry about being surreptitiously recorded. But sometimes a bit of paranoia is justified. A report by the New York Times has found that hundreds of Android and iOS games are using smartphones’ mics, not to record conversations, but to monitor users’ TV viewing habits for advertising purposes.

More than 250 games on the Google Play store were found to use software from a company called Alphonso. While the firm says it doesn’t record human speech, it can collect data on what people are watching by identifying audio signals in TV ads and shows. The information is then sold to advertisers for analysis and to improve ad targeting accuracy.

Some of the apps that use the software don’t disclose this fact, while those that do tend to bury it in descriptions that require users to click a ‘read more’ button first, which very few people ever do.

CEO Ashish Chordia told the publication that his company also works with Hollywood studios to analyze people’s big-screen viewing habits. “A lot of the folks will go and turn off their phone, but a small portion of people don’t and put it in their pocket,” he said. “In those cases, we are able to pick up in a small sample who is watching the show or the movie.”

While many of the games are available in Google’s Store, some are found on Apple’s app store. Most of these apps do not otherwise use a microphone and can monitor a mic even when they’re closed. Moreover, several of them are aimed at children, something Alphonso says it doesn’t approve of.

Chordia has defended the practice, arguing that it complies with FTC guidelines and that "the consumer is opting in knowingly and can opt out any time."

Back in October, Facebook was once again forced to deny the long-running conspiracy theory that it listens in on users’ conversations for targeted advertising. In reality, it probably doesn’t need to—the social network already knows plenty about you and your friends.