> "you don't actually have to move your lips or even open your mouth for this to work ... It's a bit weird to do"

In the video Dave just finished the training mode and is silently moving his lips, which seems pretty natural to me. I just spent a minute trying to do 'internal speech' (as many elements of speech as possible with lips closed). It does feel weird and seems like internal speech is probably providing a fair bit less signal for the system to sense (in both signal freq and amplitude). I realized I can't guess at how much articulation is 'enough' without feedback.

Based on that I'm guessing adapting to internal speech might follow a bit different path than silent speech, which seems more like 'just do what you already do silently'. Extrapolating, I expect training internal speech might involve more real-time feedback to help the user find the right degree and kind of articulation.

I realize you're still in the prototype phase but I assume an increasing number of people are getting multiple longer sessions. Do new users advance from silent to internal speech quickly and stay there? I'd be surprised as, intuitively, 'Silent -> Internal' seems like a bigger step than 'Normal -> Silent'.

Separately, if I was using it daily, I can imagine wanting to evolve a kind of micro-expression shorthand for 'Yes', 'No', 'Pause' and 'Stop', since two humans naturally evolve similar non-verbal queues over time. Vocalizing words is flexible and expressive but not efficient. It would seem odd if an intelligent, adaptive 'invisible friend' living on my face for years didn't adapt to me and me to it. Are you guys thinking in those directions for the future?