While I can respect people's rights to do whatever they want, I believe that respect is a two-way street! It's just annoying to have people play loud music without considering that someone might not be able to sleep when they hear non-stop "Guns and Roses" playing on the CD player at full blast! That behavior just isn't right!
I suggest you exhaust any option to let these people know that they are being inconsiderate. Let's hope they actually have a heart, and will honor your request for them to tone it down a bit!