I don't think that it is uncommon for dogs to be afraid of loud noises. Thunderstorms and July 4th are nightmares for my almost 13-year old mutt Gypsy. She can sense a thunderstorm coming hours before you hear a thing. Once it starts she quivers and pants the entire time--while standing on top of you, no matter if you are sitting in the couch, on a dining room chair, or sleeping in bed. Hitting rumble strips while riding in the car is a close second to thunder and lightning. Luckily the noise is brief and forgotten relatively quickly.
But nothing strikes fear into Gypsy's heart like my 10-year old daughter with a case of the hiccups. Last night I was on the couch, and I heard a faint hiccup from the kitchen. The next thing I knew I had a 55 pound quivering, panting mess climbing onto me. The shaking was so strong that the entire couch was vibrating. Even though I immediately banished the hiccupping kid upstairs, it still took Gyps a good 20 minutes to calm down.
I tried googling to see if the fear of hiccups was something other dogs experience. Apparently lots of dogs and puppies GET hiccups. But if other dogs also are completely terrified when they hear human hiccups, no one is writing about it on the internet. Except me.