https://techcrunch.com/2019/08/28/apple-is-turning-siri-audio-clip-review-off-by-default-and-bringing-it-in-house/

The top line news is that Apple is making changes to the way that Siri audio review, or ‘grading’ works across all of its devices. First, it is making audio review an explicitly opt-in process in an upcoming software update. This will be applicable for every current and future user of Siri.

Second, only Apple employees, not contractors, will review any of this opt-in audio in an effort to bring any process that uses private data closer to the company’s core processes.