If you ignore them, they take it as a challenge to get your attention and talk louder and louder. Contrary to popular belief, it is possible to avoid these people. Just remember these simple solutions and all will be well. Never look at them in the eyes, or you're a goner. Even better is the tactic of pretending that you're blind.
People act all funny around blind people and generally clam up.
Why is beyond me, since you've finally found someone who won't immediately judge you based on your looks. Please note that pretending that you are blind does not work at all if you proceed to pull out and read a book. Once again, another given. The secret here is to do nothing but raise an eyebrow or make faces at them. My friend Karon deliberately tries to scare people with strange t-shirts.