When installing a floating or laminate floor over concrete, a good rubber underlayment is very helpful to stop noise. This underlayment can be used with different types of floors. If you are renovating a multistory structure, especially an apartment complex, you want this underlayment installed to stop tenant complaints of footsteps being heard in the apartments above. This will dampen the sounds of pets, noisy kids and even vacuum cleaners, TVs and fish tank pumps. It goes down below the finished flooring layer.
Soundproofing is not done using lightweight foam. It is done using mass. The weight of rubber dampens sound. Foam underlayments can help prevent squeaking of the flooring against the subfloor, but rubber underlayment helps stop the noise of impacts, footfalls and everything else. Many renovations take into account sound reduction methods for the walls, but you need to remember to take care of the floors as well. The floor on a second story is basically the ceiling of the first story. In the old days, and probably even today, the tenant on the lower floor would rap a broom handle against the ceiling and yell at the people upstairs to be quiet.
Rubber underlayment is better than cork because it is not going to dry out and become brittle as time goes by. Its heavier mass offers more soundproofing capability as well. It may be difficult to think of installing a new floor in layers, but this is the right way to get it done. You want a floor that will last for years and help stop the transmission of sound to the floor below. The underlayment also dampens sound coming up from the floor below. Even if it is just a basement, you do not want to hear a furnace or central AC blower while you are eating dinner. Enjoy the quiet if you do your floors right.