Comment by kelnos

I think you're confusing the issue here. You were in a public place that explicitly allowed loud music with a permit. You obtained that permit, and you did what you were explicitly allowed to do. Great; you did the right thing.

But on hiking trails (and in many parks), there isn't that sort of thing. While some will prohibit loud noise, many don't say anything about loud noise. In those cases, in the absence of guidance, we should do the thing that is courteous and considerate of others: not play loud music.