The easiest way to understand this isn't happening is just to hook your phone up to a proxy like Charles, you see all network requests. If speaking automatically triggers some request you'd see it immediately (and see the URL and payload)

There was a similar conspiracy when I was in the army, about phones being able to be eavesdropped/wiretapped even when turned off. In short - they can't, but people always believed there was some super secret way to do that