I currently have three breeding pairs of quail (3 males, 3 females), with more females growing up to add to the male/female ratio. Although the roosters 'crow' is loud, it seldom lasts longer than say 10 seconds and is more of a trilling or whistling sound. I seriously doubt that a small covey of quail would cause enough noise for your neighbors to 'catch on' that the noise is coming from your yard, and if by some miracle they DO catch on, bribe them with a few eggs **winks**
Edit to add a youtube of a male quail crowing:
Edit to add a youtube of a male quail crowing: