In warning letters to 12 app developers, the Federal Trade Commission cautioned the companies about the use of software that can monitor a device's microphone to listen for audio signals that are embedded in television advertisements.

Silverpush designed software that features a "Unique Audio Beacon" technology enabling mobile applications to listen for unique codes embedded in TV audio signals. The software can then determine what television shows or advertisements are playing on a nearby television.

"This functionality is designed to run silently in the background, even while the user is not actively using the application," Maneesha Mithal, Associate Director of the Division of Privacy and Identity Protection, explained in the letters from the agency. "Using this technology, Silverpush could generate a detailed log of the television content viewed while a user's mobile phone was turned on."

Recipients of the agency's letter offered apps in the Google Play store with code similar to Silverpush, configured to access the device's microphone to collect audio information even when the application is not in use, the FTC said.

"Moreover, your application requires permission to access the mobile device's microphone prior to install, despite no evident functionality in the application that would require such access," the agency wrote in a sample letter. "Upon downloading and installing your mobile application that embeds Silverpush, we received no disclosures about the included audio beacon functionality—either contextually as part of the setup flow, in a dedicated standalone privacy policy, or anywhere else."

Silverpush has represented that its audio beacons are not currently embedded into any television programming aimed at U.S. households. But the FTC still felt the need to warn app developers.

"[I]f your application enabled third parties to monitor television-viewing habits of U.S. consumers and your statements or user interface stated or implied otherwise, this could constitute a violation of the Federal Trade Commission Act," specifically Section 5, which prohibits unfair or deceptive acts or practices in or affecting commerce, Mithal wrote. "We would encourage you to disclose this fact to potential customers, empowering them to make an informed decision about what information to disclose in exchange for using your application."

To read a sample warning letter from the FTC to an app developer, click here.

Why it matters: The warning letter emphasized the complete lack of disclosures found in the apps, with no warning to consumers of the audio beacon functionality during the downloading or installation process, either contextually or in a separate privacy notice. While the FTC noted that Silverpush represents that audio beacons are not currently embedded in any television programming in the United States, the FTC warned that if they are later embedded, the app developers could violate the FTC Act if they fail to disclose to consumers that third parties could monitor their television viewing habits. This latest series of warning letters is a reminder that the FTC is closely watching disclosures to ensure that consumers have the ability to make informed decisions regarding privacy matters.