Is the chicken coop near her house? I mean, its seems like with 4 acres, it would be far enough away to not hear any roosters.
In all honesty though, I am not happy when my neighbors get roosters either. I live in the suburbs, so not exactly the same, but even down the street I can hear someone's rooster crowing at 2am. It was the WORST when I had a newborn and wasn't getting any sleep at all in the first place. I had more than one fantasy about hunting that darn bird down and putting it out of MY misery!
If you do end up getting one, you'll have to build secure fencing and not just let them roam wild. If the dog shows up on your property, call animal control.
Have you thought about putting up fences period? Good fences = good neighbors.
In all honesty though, I am not happy when my neighbors get roosters either. I live in the suburbs, so not exactly the same, but even down the street I can hear someone's rooster crowing at 2am. It was the WORST when I had a newborn and wasn't getting any sleep at all in the first place. I had more than one fantasy about hunting that darn bird down and putting it out of MY misery!

If you do end up getting one, you'll have to build secure fencing and not just let them roam wild. If the dog shows up on your property, call animal control.
Have you thought about putting up fences period? Good fences = good neighbors.