Why don't you just get a bigger stereo and blast country music back at them, Freck?
Brick walls are there for a reason. They are not there to keep us out. The brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop people who don't want it badly enough.
Actually, contacting the representative for your district would be a good next step...
I'm wondering if these people own or rent. If they rent, the landlord ought to be notified that they are being a nuisance, and if the city gets involved, they can likely be evicted if they continue to be a nuisance.