The Hamlet Project

Who wrote their PhD on mouthing?
I would like to read it.
Because etymology on-line declares it as speaking. That’s it. Speaking.
We use it now to mean speaking without sound or even faking it, in a sense. If you’re singing along and mouthing the words, you don’t know them or the melody, or your voice is terrible. And that meaning is often overlaid onto Hamlet’s references to mouthing – both here and in his speech to the players.
Is that meaning there or are we adding it?
It seems possible that it’s there. This line suggests it a bit. It can absolutely be read this way. It can be read as fakery or just over-exaggeration, just in the way the line to the players could be.

And in performance, the overly exaggerated choice is a useful one as you can do it as you say it. But I am curious as to what other layers might be present.