Unfortunately, while our lots are good sized and the houses are pretty far apart, our chicken house is adjacent to a couple of their bedrooms, albeit at least 50 feet away. After the first complaint, we tried to figure out a way to mimimize the problem, including covering the window to make it 100% dark in the morning. We noticed quite a difference, but last week when I asked if things were better, they were not at all interested in hearing how we were working on it, and did not acknowledge any improvement at all. When we first moved in, our neighbor on the other side's rooster crowed in the morning, out in the open, and we thought it might be a problem. But we got used to it. So I'm starting to think there may be no solution (especially if insulation is not a reliable way to reduce the sound) short of getting rid of the roo, which at this point we're not willing to do. Maybe we'll try the kennel in the garage at night. We have a friend who has chickens in a neighborhood where it's not legal, and she does that successfully.
Thanks again for all your great advice.