I've never had what I would describe as a "negative" reaction to my bell ringing. But I have had a few "non-reaction" results. But who knows, maybe some of those folks were hearing impaired. I think most of the "non-reaction" folks hear the ringing and are aware I'm coming up on them, but just don't (for whatever reason) acknowledge the fact. There are no real "rules" to follow, insofar as bell ringing goes, that I'm aware of. Oh well, since I'm the one on the bike, I believe there is more of the responsibility on me to make a safe pass, the reason for the bell in the first place. Of course this is a shared responsibility (as I see it), but since I'm on the machine, and moving faster than the peds, I'll assume the lions share. YMMV.