Now to your point, vibrations from walking is a whole different beast and what I've heard works the best is if you re-do your floors upstairs, lay down some type of noise padding on top of the subfloor.Hope this helps!  

Or my foot at least after vibrating out from under the couch. instead of being grossed out, I was glad the AC was still working fine. 

The emotion, vibration will make things happen.

I don't mean the vibrations, of course.

It sounds like you might need acoustic tiles or something to dampen the footfall vibrations coming from upstairs.

I clearly stated that in my town the area by the tracks is not desirable and the trains do VIBRATE and shake houses close to the tracks...nothing stupid about that....just trying to inject some humor in my response and here NO ONE would buy or rent on the tracks !!! 

If your property doesn’t generate positive vibrations on that first peek, you can forget the brand new carpets you installed inside.Tenants and buyers alike will judge your house exactly the same way they judge a book, by it’s cover!

Lew, thank you so much for pointing that out, as I thought I do have the right to charge for extra occupant(s).Call me superstitious, I went and smudged(clear out stagnant energy and let the high vibration remain) my rental the other night.Apologize for my grammar!

Living in the upstairs unit, we can hear EVERYTHING in the downstairs apartment and can even feel the vibrations of their footsteps sometimes.

The vibration is created at that point and therefore the vibration is transferred much more efficiently.