Just additive cancilation?
The common way to use two microphones is just to wire them together. So why are they using a signal processor? Are they using a delay loop so they can try mounting the two microphones further apart?
The more interesting thing that you can do with two microphones and a signal processor is, you can cancel noise at the earphone, to make it easier to hear the conversation. People know about that, but no one ever actually does it.
The most interesting thing you can do is predictive noise cancelation of cyclic signals - like car engine and road noise. If they are trying that, I wish someone would say so.