"Quiet" is a misnomer for the autist. It is "quiet" in my house now as I listen to the blaring of what are just background noises to you. The computer buzzes, refrigerator hums, and dish washer wooshes its way through cycle. I am distracted by all; each takes its turn. Sometimes a planned noise helps create what is quiet for me, it sings a soul song. I put on the radio and let the rhythm sooth my soul. It organizes my attention, focusing it on something singularly directed.
Facilitation is an exercise in dealing with background noise. Each variable in typing is its own background noise. It is easy to get lost in it. What is needed is a focus point. For each of us, the focus point may differ I think. For some, it is the message itself. For others, it is an internal rhythm set to type to. I used to type from the feel of Mom's heartbeat throbbing in my finger. Now I try to feel my own heartbeat as rhythm. Some work to the rhythm of returning to a common end point. I type moving letter to letter, but it might have been easier to learn to type as endpoint to letter to endpoint, repeat. The freezes you see are hiccups to our motor rhythm. Using planned noise can help with it. Your prompting is a form of planned noise. In building independence the key is to transfer the source and control of the planned noise from you to me. Depending on the autist the necessary sensory mode would vary as effective. Visual sound I can't talk to. I don't experience it. But I imagine a visual field could be designed with flow. I use auditory and tactile sound to move past freezing. The sound of a feedback stylus (a clicker pen), the sound of a token hitting the board, the rhythm of a piece of music or ticking of a clock, each is enough to move my motor past its natural stall point. Finding the right planned sound is an art beyond skill, individual to each of us. But finding it means first knowing enough to look for it. It is all I can offer you sometimes; to know what is the question.