Teaching learners who only learn by sound memory I wonder whether the distinction between ringing by the tune and ringing by path.
When I'm ringing handbells I'm often not aware of the actual place each hand is in. Im aware of the overall pattern and largely 'feeling' my way through it while listening to the sound, which does feel as if I know it in some sense, though I can't fully know it whe ringing a quarter. I suspect my brain has learnt some aspect of the structure that enables it to predict what comes next from what I have just heard, though perhaps not all the time.
I suspect my brain might also be simplifying the sound in terms of 'my bells' and 'other bells' so a lead will sound familiar if my bells follow the same path even if some of the thorns don't.
This is speculation of course, and when ringing I don't have a lot of spare attention to think about what i am hearing.
Also I'm much less conscious of any similar effect in the tower so it might not read across to the person in the original question. But it does suggest there might be more of a continuum between different ways of knowing what to do.