To scare dogs.
I heard nearby fireworks last night and dogs even more close went nuts, and I thought, come on, take care of your dogs. Surely, you hear both those things.
One day in the backyard I was reading (Aztec, Gary Jennings) and nearly sleeping when a firecracker went off a few blocks away and I think that I heard the report like a dog does. I was startled by two sounds it makes, and my immediate thought was, so that's how she hears it. And I understood the how "kapow" is the onomatopoeia, I could almost see the sound waves, the precise point of origin like a pin on a map exploding nearby then the wall of sound suddenly RIGHT ON YOU, an extremely aggressive assault in sound with palpable physical quality, and I understood why my dog is so terrified. There is no escaping the attack. It's the sound of an overpowering direct attack, right at you. I felt tremendous sympathy for my dog who felt so helpless. I had to create a safe place for her, a shelter for her to hide, deeply as she could go but still home. For several days. The cool basement was farthest she could go, with her security blanket and toys and a radio set to the classic station, KVOD, and just hope they didn't play Sousa.