It is amazing how so many folk (pedestrians and 'cyclists') ignore the ringing of a bell, 'excuse me' and general noise-making...
Ping bells are hard to hear, difficult to sense direction of, and sound like tinnitus or builders dropping things. Brrrring bells sound like somebody's phone. When you're on your own people speaking/shouting are usually talking to somebody else, unless they're A Threat, in which case the best approach is not to (visibly) react. But mostly it's just not paying attention.
I will use bells or speech on shared paths, but I generally find that a deliberately noisy gear change is the second best way to get people's attention without alarming or offending them. (The best is the sound of studded tyres on brick, but that's not usually practical. Third best is a decent front light, but that only works when it's dark.)