Thanks to OP for signposting this survey. I use the towpath daily for dog walking and regularly for cycling. I also kayak on the canal frequently (I will save comments about other watercraft and fishermen from a kayaker's perspective for elsewhere!). Am sure I easily qualify as a gongoozler by now!
I am deaf and even with hearing aids in don't hear cycle bells. I usually walk to the side of the towpath with the dog and keep an eye out for things behind me. Despite this, quite often I get surprised when a bike zooms up quickly from behind, presumably ringing its bell and comes really close before I realize. Without wearing a big sign on my back saying I have impaired hearing there isn't really any way of forewarning people. When cycling on the towpath myself I am now much more aware of the need to check walkers response to my own bell (which I can't hear myself) and I moderate my approach and pass by accordingly.
Lots of people are hearing impaired but most don't persevere with aids as they are hard work to start using when you are older. After all this, I am saying to cyclists not to assume a walker is being rude or inconsiderate if they don't respond to bells or calls from behind until you are frighteningly close!