While not a defence exactly, aversion therapy works with average bears.
Start by carrying one of the small areosol sports horns. You can find them in most any sports store. They scare the hell out of the average black bear, while not scaring the wife. Do what you can to not encourage the bears in thinking your house is a drive thru restaurant. Forget the bird feaders and outside garbage and trash.
Bear spray won't alarm you neighbors as much as a round going off. So if you've got reports etc. of agressive bears in the area, by all means have some handy. You're probably in more danger of a rabid fox or racoon than you are from the normal black bear.
Myself, in bear or pig country I carry a .44 Redhawk with a 5" bbl on a belt holster. The hell with concealment, I want accessibility.
Sorry this wasn't what you asked exactly, but it might be a better way of handling things.

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Pete.