Recently I noticed a disturbing amount of rattle from the outside of my doors when my music was on. You might not even know you have this problem, unless you turn on your stereo, close the doors, and listen from the outside. Some may say who cares if I don't hear it inside, but trust me it sounds like absolute crap. This is how I fixed it.
First, I utilized the following link from Andrew6@TheDoubleAA that demonstrates how to remove the door trim:
Here is picture of the driver's side door with the trim removed, after I started dynamating it. You need to remove the pliable membrane to access the inner part of the door. (Note
: I didn't replace it, and haven't noticed any issue.)
The root issue is the outer door skin vibrating against the ribbed structural support. By wedging some two inches strips of dynamat into the crease the rattle is now gone. Not to mention, the quality of sound is better in my book.