Hello gentlemen! So I have a situation. Concrete floor (ceiling actually) slabs like these has many cylindrical spaces in it. And noisy neighbors on top! The slab receives shocks / impacts and human shouts. First I found Tuned Mass Damper. It is good for continuous vibration but not for first cycles after vibration applied. I mean shock is sort of "1-cycle vibration". May be if I pump some kind of oil or solution of calculated density inside that slab it could absorb impact energy and convert it to waves or something... Frequency range to be muted is about 10Hz - 3400Hz I think (it would be great to cover even short part of it). I would like to hear your advice what you think could be done here?