Neighbor noise can drive anyone crazy. Imagine a loud stereo next door. This airborne noise immediately enters his wall drywall and vibrates the wall studs in the wall between the two of you.
In turn, this vibration will race through the wall framing and start entering your room. The framing is very conductive, so vibration passes through very easily. Your wall drywall is rigidly attached to this vibrating framing, so the vibration easily enters your wall drywall and then hits you. The video below sums it up nicely.
Solutions for Soundproofing your walls
We would prefer to treat the wall from his side to immediately destroy the vibration before it gets into your wall framing. This is generally not possible, and he probably doesn’t want to help you anyway. So really all you can do is treat the wall on your side..
Option 1 – Add drywall and Green Glue
Add two layers of standard 5/8” drywall and Green Glue. Make the wall as heavy as possible with standard $8 drywall. Install a medium coverage of Green Glue between the layers. This will reduce a great deal of the vibration, but certainly not all, since the vibration is racing through the wall framing behind the new drywall layer.
Option 2 – Remove drywall & add Sound Isolation Clips to the wall framing members
Remove your existing wall drywall and install standard R13 fiberglass (nothing thicker or expensive).
Then install the less expensive decoupling clips and channel. This will reduce the physical contact points when you add your new drywall and quite effectively decouple your new drywall from that original wall framing. Then double drywall and Green Glue. This solution utilizes all 4 Elements of Soundproofing.