As noted above, some sound proofing will help. I have neighbors very nearby and having a roo has been a great worry (even tho I love the sound and find it pure pleasure compared to that of an incessantly barking dog).
My coop is insulated and in the winter with windows shut I don't think anyone hears him since their houses are also closed up with the cold weather. It is more of a worry in the late spring and early fall when the weather is so nice that neighbors have their windows open, and when the coop windows are also open. On the opposite end of the spectrum, when it is insanely hot out, neighbors have their windows shut and AC on so that muffles sound.
I try as often as possible to keep them in the coop till at least 8 so the full strength of his crow is not heard until after that hour. This is hard with work but I do my best, because I don't want the neighbors to complain and create a problem with me keeping him.
Luckily my guy doesn't crow much during the day, some days not at all. He tends to belt out some happy crows on particularly gorgeous days and I run to distract him if I'm home because even though I love it, again I worry about the neighbors....if someone wanted to make trouble they could....never mind that their dogs, chainsaws, leaf blowers etc. are infinitely louder and more annoying!
JJ