I regularly ride on shared paths. I find that even when there are markings to show which half pedestrians use, they still walk on the bike bit all the time, or wander into it at random. Traditional bells are probably the best, especially to warn older people. There are kids around today who have never heard a traditional bell, and are unaware what it means, even if they can hear it despite their earphones.
I feel that it is important to avoid using any warning instrument aggressively, as it can upset people. I chose a large two tone "Ding Dong" bell, because it is loud. I give a first warning when i am still 100 yards away. If there is no reaction, it is repeated at 50 yards, and ten yards.
In spite of this, I still had a guy step in front of me. He said he had heard the bell, but "Thought it was somebody`s doorbell". The nearest house was a couple of miles away.
My pet hate is extending dog leads. Dog and owner are separated by five metres. Invariably, the dog is one side of the path, and the owner the other. Just what is the supposed advantage of these leads?