I have 23 birds about 7 weeks old. They are crowing like crazy but with just that few birds, it is not so bad. If you get 40 or 50 crowing all at once, then it gets loud. I actually have wild birds in my yard that make a heck of a lot more noise than the quail. I think that maybe the folks in my neighborhood just think they are some strange bird or crow. I do hear them in the middle of the night sometimes and it makes me want to remove their heads!
I think I have 5 hens out of the 23 so the roos are fighting and crowing more than normal. I have been debeaking right and left the last few days trying to discourage fighting.
But a few quail with a about 4 or 5 hens to one roo is ideal. You will hardly ever hear them make much noise at all.