
Best thing is just to act as if you can't hear anything! Don't respond to the noise at all - don't make eye contact with the pup. If he can see you're not bothered, it's more than likely he'll copy you ....
:)
Edit: An alternative is to randomly drop titbits near him when a particularly loud bang goes off (you should be watching his reactions out of the corner of your eye) - if he starts to associate bangs with titbits, he's not likely to be too upset!