Soundproofing Impact Noise from Below?!

[revsteve]

First let me say this board has some great information on it. 

Second, my girlfriend and I are suffering from some loud neighbors who have very heavy feet.  We live on third (and top) story of a condo complex.  We just had someone recently move in to the unit below ours.  Since then, we have been awakened almost every night by loud walking or doors slamming at all hours (usually between 12 and 2).

We have already attempted to talk to them about their living condition, but they have been very aggressive and even threatening with us so this really isnt an option. 

Can anyone suggest how to eliminate this impact noise coming from below?

[Randy S]

RevSteve,
In your situation your are chasing structure borne and impact noise from the receiving side and this will make it more difficult to get results. You will need to address the floor,walls and ceiling to get a reduction of remitted impact noise. I would suggest doing a second layer of drywall 5/8" or thicker and a 3 tube per 4'x8' sheet drywall of Green Glue for the walls ceiling.
http://www.soundproofing.org/ggpages.htm
 And for your floor I would use MLV w/ Closed cell foam underlayment, wall to wall.
http://www.soundproofing.org/infopages/flooring.htm

This will dampen the walls and ceiling and give you a sound and impact barrier over your floor.
Your other option would be decoupling the walls and ceiling from the structure, which would entail taking down all current drywall and floating walls and ceiling on sound clips and channel.