The key to combating sound bleed through a common wall or ceiling/floor assembly is to break the connection points and line the common assembly with more density.   The disconnection comes in the form of a channel system that can be anchored to an existing, finished wall.  This is like snipping the string pulled tight between two coffee cans.   Without the disconnection, regardless of what you anchor to your wall, vibrations can push through structurally and become airborne next door.

The density comes in a variety of forms.   Layering your treatment is more important than putting a single weighted panel up on your wall.  Layering mass loaded vinyl, such as dB-Bloc, then a channel system and a new layer of drywall can combine to collapse up to 90% of transmitting noise.   Without the weight, your percentages drop dramatically.

Some vendors in today’s market offer the density embedded into the drywall itself, rather than layered up behind the drywall.   This is the equivalent to wearing one bulky sweater in cold weather, rather than layer your clothing to stay warm.   A single, dense panel that is simply applied to a common wall does less to combat sound bleed than does the same density first layered up separate, with a dead air pocket defined by your channel system, and then a standard layer of drywall.  Density, air gap, density outperforms density alone.   Food for thought if you are considering pre-engineered drywall.   For more information on soundproofing your wall, call NetWell Noise Control at 1-800-638-9355.