Help! Everything is soundproof! except....

the floor. I spent all of March building my project studio in an NYC office building. It came out amazing! very little bass leakage to the adjacent rooms and room above. Overall, I'm very happy with it. However, I took many people's advice and didn't isolate the floor. Someone moved in downstairs with 1) a loud voice 2) a baby that visits every day from 4-5 and 3) the worst.... a rolling chair on a wood floor that resonates up through my walls! He also has complained about the impact noise from my electronic kick drum pedal. It got so bad at one point last month that we had a small shout between the floor (his ceiling) involving a few words that aren't fit for public display. My floor is simply plywood and I threw a small rug over it. Building a new floor at this point is out of the question. Are there any treatments that might help me here? Perhaps carpeting the entire room? Maybe throwing down a dense sheet of something covered by carpet? Anything to help isolate us would be great. Thanks.