I haven't had that issue, but there is a thick mat that can be installed under some flooring that reduces the transmission of high to medium frequencies. They can't stop the bass from the stereo, or stomping, but the heel clicking and voices are reduced.

https://www.google.com/?gws_rd=ssl#q=sound+reduction+wood+floor+underlay

Look for real-world lab results and decibel reduction. It's something that adds a lot of value to the space. DIY versus requiring a pro might be an issue, and it will affect the kind of flooring you can install (no nail-down tongue and groove)

For maximum sound reduction, also use caulking (regular or sound reducing) around the edges of the flooring to eliminate places where sound can flow out of your place and into the lower one. It has the secondary benefit of minimizing drafts and bugs.

Great tips Lazygardens, thanks.