Washington, DC - The staff of the Federal Trade Commission has issued warning letters to app developers who have installed a piece of software that can monitor a device’s microphone to listen for audio signals that are embedded in television advertisements.

Known as Silverpush, the software is designed to monitor consumers’ television use through the use of “audio beacons” emitted by TVs, which consumers can’t hear but can be detected by the software. The letters note that the software would be capable of producing a detailed log of the television content viewed while a user’s mobile device was turned on for the purpose of targeted advertising and analytics.

The letters note that Silverpush has stated publicly that its service is not currently in use in the United States, but it encourages app developers to notify consumers that their app could allow third parties to monitor consumers’ television viewing habits should the software begin to be used in the United States.

"These apps were capable of listening in the background and collecting information about consumers without notifying them," said Jessica Rich, Director of the FTC’s Bureau of Consumer Protection. "Companies should tell people what information is collected, how it is collected, and who it’s shared with.”

The warning letters note that app developers ask users for permission to use the device’s microphone, despite the apps not appearing to have a need for that functionality. The letters also note that nowhere do the apps in question provide notice that the app could monitor television-viewing habits, even if the app is not in use.

The letters warn the app developers that if their statements or user interface  state or imply that the apps in question are not collecting and transmitting television viewing data when in fact they do, that the app developers could be in violation of Section 5 of the FTC Act. The FTC provided guidance in a 2013 staff report on best practices for privacy disclosures in mobile apps.

The letters were issued to 12 app developers whose apps are available for download in the Google Play store and appear to include the Silverpush code.