I’m surprised that these seemingly normal sounds would disturb you neighbors…the sounds of the rabbits doesn’t seem out of place with what normal humans would make.
One bunny sound that I could believe making a difference is their thumping. My previous rabbit, Bunny, could make an astoundingly loud thump. She was about 8 pounds. Trying to make the same sound, I put my elbow on the floor, raised my fist about 1 1/2 feet above the floor and then slammed down my fist. That made about the same sound!!!! Bunny, who slept in our bedroom, would occasionally thump maybe once or twice. I never knew really why. Maybe an animal outside the house or under the house crawl way. But one thing…in the 11 1/2 years we were blessed to have her, when she started thumping continually like maybe twice a second and just continuing on and on…she was warning us about something important! One situation was a large plastic trash can sitting adjacent to our house, under the eaves of the roof, was ablase. The flames were not that far from setting the roof eaves on fire. (Grandson tossed a cigarette butt into the trash can.) Bunnies have superb hearing and smell, pretty good eyesight also. Because they fear predators, they make pretty good watch dogs. Your bunny will start thumping if it fears you and it are in danger.
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My two Flemmish babies are now big…12 pounds at 8 months old. They will occasionally thump, but it’s not too loud. I think these thumps are communications between the two. If one is in one part of the house, and she wants the other to join her, she will thump and her sister will run to her. As they move around the house, they seem to know where each other is! I’ve seen them being in different parts of the house and run up and join each other without thumping.