Facebook Inc. (FB) is at it again. As the leading social media giant continues to face questions around privacy issues and exploitation of user’s personal data, a newly unearthed patent application filed in December 2016 by the company that may raise new questions of how much intrusion technology can have in a user’s life.

The patent details how secret inaudible messages in television ads can trigger an app installed on a smartphone to use the device's mic to record key details, according to news portal ArsTechnica. Those recordings, presumably without user’s knowledge, can then provide indications about how those TV ads played out in an average user’s home. (See also: Facebook's Next Privacy Controversy is Biometrics.)

How the Secret Recording System Works

U.K. news tabloid Metro explains the working of the system described in the patent.

Connected devices like phones with installed apps get trigged by signals hidden in ads or other content that may be inaudible to human ears. Once triggered, the devices start recording. A user's reaction is then analyzed and stored online along with user’s identity. The data can then be used to conclude whether the user watched an ad, engaged with the content or simply ignored it. The Metro report adds, “If a recording of the hidden code is muffled or distant, it would indicate users are far away from the [television]. Whilst a loud, clear signal would suggest they were firmly couch-bound and tuned in.”

Such details are key pointers to content providers and advertisers who can use it to show influential ads to the users that they are likely to engage with.

Implications of the Patent

Deciphering the patent’s language description, ArsTechnica reports the purpose of this technology: “to determine whether or not a broadcast viewer listens to full or at least significant portions of content like advertisements, and to pass that information back to Facebook.” For example, it appears possible that this mechanism can capture and report back to Facebook whether a TV viewer skipped the ad completely.

While questions may be raised for the world’s leading social media giant for seeking patent on such an “intrusive-looking” mechanism, Facebook VP Allen Lo offers a two-point justification. First, patents often focus on speculative technology of the future that “could be commercialized by other companies," and, second, the patent was filed to "prevent aggression from other companies." He further adds that the patent will "never" be implemented in a Facebook product. (See also: Will Privacy Issues Ruin Facebook's Business Model?)