Facebook has admitted that it has been transcribing audio chats between its users on its Messenger platform. Hundreds of contractors reportedly were hired to transcribe Messenger voice chats in order to test the accuracy of an AI algorithm. Facebook could find itself afoul of the General Data Protection Regulation (GDPR) in Europe due to this lack of clear data processing policies. Apple, Google and Amazon have all landed in hot water over the way they collect audio clips from users and use humans to review them from users.
Source: https://threatpost.com/facebook-records-user-audio-privacy/147314/