During an appearance before a committee of U.K. lawmakers today, Cambridge Analytica whistleblower Christopher Wylie breathed new life into longstanding rumors that the Facebook app listens to its users in order to target advertisements.

Damian Collins, a member of parliament who chaired the committee, asked whether the Facebook app might listen to what users are discussing and use it to prioritize certain ads.

“That’s probably a question for Facebook,” Wylie said.

But, Wylie said in a meandering reply, it’s possible that Facebook and other smartphone apps are listening in for reasons other than speech recognition. Specifically, he said, they might be trying to ascertain what type of environment a user is in in order to “improve the contextual value of the advertising itself.”

“There’s audio that could be useful just in terms of, are you in an office environment, are you outside, are you watching TV, what are you doing right now?” Wylie said, without elaborating on how that information could help target ads.

Facebook has long denied that its app analyzes audio in order to customize ads. But users have often reported mentioning a product that they’ve never expressed an interest in online — and then being inundated with online ads for it. Reddit users, in particular, spend time collecting what they purport to be evidence that Facebook is listening to users in a particular way, such as “micro-samples” of a few seconds rather than full-on continuous natural language processing.

A Facebook representative did not immediately reply to a request for comment on Wylie’s statement. It’s not clear how Wylie would have any insight into what data the Facebook app collects.

Privacy activist Paul-Olivier Dehaye, who appeared alongside Wylie at the committee, offered a more philosophical answer to Collins’ question.

“I’m not convinced it would be so hard to implement,” Dehaye said of the possibility that the app is listening in. “But I just have a general comment, that Facebook is so opaque that people start [guessing and] clutching at straws at what explains all this targeting.”

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