Pompiere

If your chain alignment is far enough off, you might feel the vibration through the frame, but you might not hear minor rubbing after a shift. But if you already are having hearing loss, it would be very difficult to learn friction shifting without hearing the feedback of the chain rub to fine tune the lever position. If you use friction shifting long enough, you develop muscle memory so that you can move the lever just the right amount to shift a gear. It's much the same as a trombone player knows how far to move the slide, or a violin player knows where to put their fingers.