Easy to install, this noise reducing product can be added at nearly any stage of a project. It's most often used for living areas in boats and for architectural applications.
Anyplace where the flooring is a significant source of noise, carpet underlayment is an effective treatment. It consists of a layer of foam (bottom) supporting a vinyl acoustic barrier. This decoupled mass is available in various weights and thicknesses, so you can choose the most effective without compromising too much headroom. It can be used to augment almost any other noise reduction treatment, both structureborne and airborne.