Loud, booming, rumbling coming from the sky.The 22nd of August, myself, my husband, our dog, and father were near Lawe St and Lamplighter Dr in Kaukauna, where we heard at least 3 LONG sets of incredibly loud sounds coming from the sky without any objects in sight. They were unlike anything any of us had heard before; somewhat like repeated exchanges of gunfire, but much louder and deeper. There were long bursts of booming and rumbling that sometimes appeared to grow louder and closer to you as if it was following you. The first 2 times we were a bit unnerved and curious...but by the 3rd set, we were actually pretty frightened. At first my dog had no discernable response (as she would, for example, to fireworks). By the last set of sounds she was uncharacteristically, whining, sniffing the air, pulling at her leash and panting. Each set lasted from 40 seconds to over a minute and a half. I waited to watch/read local news before reporting/documenting here. There's been nothing to explain what we heard.