I’m unconvinced. I have a voice in my head that is always there flowing words while thinking. Actually being able to speak maybe different than running words through your head.
I also think that maybe not every task requires the head voice, and visual pattern matching was the first thing I considered that might run an orthogonal path. But it would have to be simple. If you start doing IQ puzzles I have my doubts. I do wonder though how someone who was deaf at birth functions.
Some people don't have that.
Not sure why this is surprising. Language is a communication protocol