The outer walls in most basements will be concrete block or poured cement. The inner walls defining the rooms in a basement will be wooden stick frame. Four walls, two concrete, two wood frame is the standard starting point for a client attempting to hold noise to within a room in the basement. The room might be a home theater, a drum rehearsal space, a bedroom or a furnace room. Regardless of the noise source, if your goal is to contain the noise, don’t ignore the walls.
Treating the ceiling for sound bleed is important, yes. The layering sequence of anchoring mass loaded vinyl and a resilient channel system to your ceiling prior to your drywall can knock out up to 90% of the sound bleed. The key mistake most clients make is ignoring the walls in a basement, thinking that they don’t see the need to isolate sound bleeding through the walls. But what they fail to recognize is that the walls become a carrier for the vibration, pulling structure born sound upstairs, circumventing the ceiling treatment.
So to properly soundproof a room in a basement, don’t ignore the walls. Layer the same mass loaded vinyl treatment to the walls as you do to the ceiling, and for the collapse of the connection points, and thus the collapse of the noise bleed. For more information on this treatment, see the dB-Bloc section of a website www.controlnoise.com.