I hope your handgun is something like a .454 Casull, .460 S&W or .500 S&W. Bears don't go down easily, even the little black ones. Noise may not work either.

Here's a report of a bear near where I live, and what it took to stop it. Mind you, this was a 120lb bear. My dog weighs 145lbs (and looks kind of like a bear too!)

http://www.denverpost.com/ci_12927288

The synopsis:
Quote:
It took three rounds from a shotgun, five bullets from a handgun and two shots from a rifle to kill a 120-pound, juvenile male black bear that broke into a Boulder County home early Monday.


With the shotgun:
Quote:
"As soon as I moved to try and make a place for him to get out, he charged me," Paul Fischer continued. "That's when I shot him, and he kept charging me. I shot him a second time, and he kept charging me. I shot him a third time, and he was finally disoriented enough for me to get away."


With the handgun:
Quote:
After determining that the bear was severely injured and would need to be put down, sheriff's Sgt. Lance Enholm fired his .45-caliber handgun five times at the animal.

"(The first shot) struck the bear in the head, and it immediately reacted and began flopping around and growling," Enholm wrote in his report. ". . . I fired another round from my handgun, again striking the bear in the head. This didn't appear to have any impact on the bear, and it kept coming towards me."


And finally, the rifle:
Quote:
It was shot No. 9, this time from the sergeant's .223-caliber rifle, that finally felled the bear.


Tough little bugger. Didn't seem to be terribly afraid of the gunfire noise either. I think your blanks are a good idea to try. You may get lucky and be able to frighten a bear off. But I don't think I'd want to actually shoot a bear, any bear, and risk irritating it ... with anything less than a .45-70 rifle.