Need advice for sound proofing a duplex

[Taig Blum]

I plan on moving into a duplex and renting the other side out. When owning a duplex is there anything you can do to help cancel sound between the two units? 

[Matthew Paul]

Yes , heres what I did . I removed the drywall on 1 side , framed another 2x4 wall up against the original wall , I put in insulation , and hung 2 layers of 1/2 inch drywall on 1 side , and then went to the other side and put up 1 layer of drywall over what was there .   To check we cranked up the radio on 1 side then walked next door . You could barely hear it