The head of Facebook's US-based Security Infrastructure team has defended a recent app update that uses a smartphone's microphone for Shazam-like audio recognition.
The feature was announced at the end of May, and was expected to roll out within weeks. Allowing Android and iOS users to "identify TV and music instantly," the app is capable of recording ambient sounds in the user's environment to recognise what show is on the TV or what song is playing.
While the functionality is opt-in for users and only available in the United States, the announcement quickly raised concerns that Facebook was equipping smartphones to record private conversations or user activity.
However, head of Facebook's Security Infrastructure team, Gregg Stefancik, has moved to reassure users that the social network is not listening in or storing conversations, saying there were a "a lot of myths" about the new feature.
"First and foremost, the feature is opt-in for users," he said. "We're not doing it without the user consent."
According to Stefancik, the app creates an "audio fingerprint" from the smartphone-recorded sound (a process which cannot be reversed) and this fingerprint is matched to Facebook's database of songs and television shows.
"If there's a match, we return what the match is to the user [and] give them the option of posting the match. The user is in complete control and the audio fingerprint that we've received is disposed of immediately. The raw audio never leaves the phone and the data about the match is only stored if you choose to post it."
Importantly, Stefancik added that it was not an 'always-on' feature.
"The microphone doesn't turn itself on, it will ask for permission," he said. "It's not always listening... so it's very limited in what it is sampling.
"I wouldn't want this in my pocket either if it was recording everything going on around me."
Update June 5, 2014: A Facebook spokesperson has clarified details on how data is stored. "If we find a match and you don't post, we log that a particular song or TV show was matched, but we don't connect this with your profile in any way," the spokesperson said. "We use this to keep a chart of the most watched and listened to songs and TV shows."