Originally posted by binka_nugget
I don't know how true this is but I've heard that reassuring while the dog is afraid is interpreted as praise by the dog. I know one group of people who say to never pet and baby talk a dog while it's afraid, and another group of people who say it's completely fine to cuddle and talk to it softly while it's afraid.
You are absolutely correct, you should not "baby" a pup when they are having a fearful reaction. Otherwise it inadvertently reinforces the fear reaction. What you can do, however, is try to act as matter of fact as possible - talking to your dog is great as long as you do it the same way as any other time. You need to come across to your dog that it is "no big deal". You might want to engage the dog in a play session or a training session - which will distract them from the loud noises. Both Leo and Penny are scared of fireworks, so the week of Fourth of July - I have their crates in the basement where they seem to feel the safest. I leave the door open to the upstairs, but they will go down there when it gets too loud or are frightened.

Generally a dog that gets older starts to loose some of the hearing. I find it interesting that your dog is becoming more sensitive to loud noises. It could have been something that frightened him when you weren't home and he is associated all noises with this thing. Buster, my RB dog when he was about 8 years old inadvertently knocked a vase off a shelf which shattered right next to him. He was petrified of all loud noises from that point on.