Multiple layers of materials are used to diminish sound transference. Challenge will be multiple issues: 1. If there is hvac vents shared, that will pass sound 2. There will be some frequencies that will pass louder than others with multiple layers. Carpeting will help. Padding will help. Insulation will help between the floors. 3. Hiring a company that does this sort of thing takes you out of the discussion, and might be worth considering 4. What is the home owner expecting?
