Walls that bleed noise are typically not heavy enough to withstand resonance, and structurally not disconnected enough to force the collapse of the trasnmitting sound wave. Think of a string pulled tightly between two cans, with your voice carrying through the vibration of the string. Well, the studs inside your wall cavity are connecting your two rooms together, and deliverying the same net effect. Stuffing batting insulation between those studs is a futile exercise, as it is ignoring the essential path that the noise is taking to transmit through…it is structure born vibrations that are the hidden culprit.
To properly insulate a wall against sound bleed, two components need to be added to the wall, whether it is a new build, remodel, exposed frame or finisihed surface you are starting with. In any of these cases, your goal is to “snip the string” that is connecting the rooms together. Furring strips, resilient channels or hat channels can be applied to an exisitnig finished surface and drywalled over. For new builds, a double wall or staggered stud wall assembly means no furring strip is needed. Any of these will force the collapse of the vibration, the snipping of the string.
The second ingredient required in a sound isolated wall is density. Think of a tuning fork, a drum, a guitar string or a wine glass. So long as these objects are allowed to vibrate, they will produce sound, right? But touch any of them with the palm of your hand, and the sound dies instantly. Mass kills vibration. The same treatment should be put on a wall, to prevent the surface from being able to accept resonance. In the market today, the most popular technique is a mass loaded vinyl called dB-Bloc, which is a thin, dense layering membrane that embeds behind your final drywall layer.
So the technique? Add dB-Bloc to your walls, then a furring strip system, then new drywall, and you’ve got a nice STC value. Each treatment will trigger varying results based on leakage and decay, ventilation systems, outlet plates, plumbing fixtures, floors, ceilings and more, but to combat the bulk of the noise bleeding structurally straight through your walls, go with dB-Bloc. Sold in 54″ x 30′ rolls right here at NetWell Noise Control. Good luck!
For help with a common wall sound issue, or any other acoustic project, call the help desk at NetWell Noise Control for free consultation. 1-800-638-9355. Or visit us online at www.controlnoise.com.