I start out with my bell, if I fail to see anything from the pedestrian (or fellow bike rider) that indicates they are aware I then call out. Sometimes they are completely zoned out, or as the above posters mention - have those dratted earbuds in and the music cranked up.

One guy I dinged my bell at, he continued to drift left, I dinged some more then called out . . . nothing. I called out louder and closer and still got no response. I just crept behind him till he wandered right again and cautiously passed him. I thought he was going to have a coronary right there. He jerked so hard it was a wonder he didn't get whiplash. He actually screamed like a girl and jumped. He then yanked his buds and started to lay into me verbally. I just shrugged and continued on. Gotta pick your battles and arguing with this guy was probably not going to net me anything.

I actually was thinking on how much it would weigh and how many blasts I could get out of an old air tank and truck horn I have sitting around in my garage. I think that would cause more issues than it resolved.

It happens.