Okay, since you are kind enough to respond... If you're up for it, can you test this? It sounds ridiculous, but in a dark small room, whispering as quietly as possible, can you verify that you stutter? Maybe repeat something you know by heart. If you do stutter, can you then simply mouth the words with no sound coming out? Do you ''shutter'' when you do that? Again, this is quite interesting to me as it's generally not the case that we stutter alone. So i'm curious about your threshold. No worries if you're not interested in trying this. But if you are, i'm very interested in the result.