insulation between floors?

Sound Attenuation Batts (SABs) are lightweight, flexible fiber glass insulation batts. They are designed to deliver noise control in metal stud wall cavities of interior partitions. The friction-fit installation, light weight and longer length help speed installation and virtually eliminate acoustic performance problems.

I’m not familiar with these, Marcel. Please educate me a little more here…

Basically, sound is transmitted through walls through the air spaces in uninsulated stud bays and through the (wood or steel) framing. The majority of sound is transmitted through the framing because it forms what we might call a solid sound transmission “bridge” from one side of the wall to the other.
Solid wood and steel both conduct sound waves more efficiently than air, that’s why they’re called a “bridge”.

Insulation might reduce the transmission of sound from one side of the wall to the other by either reducing the transmission of sound through the air in the stud bays, which seems plausible, or by reducing the transmission of sound through the framing members with which the insulation is in contact. That I don’t understand so well.

How do these SOBs work?:mrgreen:

They are pretty much regular insulation batts with a jazzed up name…it’s all marketing!!!

Here’s something from the Owens-Corning Q&A site:

What are the acoustical qualities of QuietZone® acoustic batts compared to R-11?

The acoustical performance of QuietZone® acoustic batts are similar to R-11.
Note - if QuietZone® acoustic batts are not available in your area, R-11 fiber glass insulation would be an acceptable substitute. Do not use QuietZone® on exterior walls as the facing is not a vapor retarder. R-13 or R-15 fiber glass batt insulation is recommended for exterior walls.

Quite Zone is a system not just an insulation.
The Quietzone™ stud is designed to be 1/8" wider than a conventional stud. This allows the attached drywall to float outwards from the top and bottom plate, effectively breaking the sound vibration path through the wall. Quietzone™ ? Acoustic Caulking is used to seal the gap between the drywall and top and bottom plate. This assures that the wall assembly is well sealed and able to vibrate freely. Quietzone™ caulk is designed not to harden and will remain elastic over time.

There is not much difference in the Sound qualities with regular batt insulation and most people use it.
Commercial projects are told to use sound attenuation blankets as specified and all manufactures of insulation have it available.

Subjective Effect of Change in sound Pressure Levels;

3db Just perceptible
5db Clearly noticeable
10 db Twice as loud
15db Big change
20 db Much louder (or quieter)

Very often these tests are used to support acoustic modeling efforts. Acoustic modeling is done in order to predict and then optimize the performance of a material or system using computer simulation. By using the output from the above material property characterizations, a simulation of materials or layers of materials can be created by Acoustic material specialists using specialized modeling programs. These models can determine the Transmission Loss of complex composite materials and systems as well as their Absorption Coefficients. This allows the engineer/designer to evaluate hundreds of different configurations of materials and systems without having to build expensive test components. The Owens Corning staff can work with your engineers to help create these models and help to optimize the acoustic properties of their designs.

*Sound Transmission Class is measured in accordance to ASTM E 90 test methods, which measure the transmission loss characteristics of a partition. Depending on the wall construction, substantially higher (than 10dB) dB reductions can be achieved depending on what type of wall, ceiling, or floor systems are being compared. A laboratory test of a typical untreated interior wall has an STC of 35. Our 2” x 4” QuietZone® Acoustic Wall Framing when used with QuietZone® Acoustic Batts and QuietZone® Acoustic Caulk receives a rating of STC 49, a 14 dB reduction in sound transmission.
The sound performance of a wall or ceiling is given a number rating called STC, or Sound Transmission Class. The higher the number, the better the sound control.
Another rating, the IIC (Impact Insulation Class), is used to describe the sound control performance of floor/ceilings on impact sounds, such as footfalls or moving furniture.

As an example, standard wall construction containing 3 1/2" of insulation with a single layer of 1/2"-inch gypsum board on each side produces an STC of 39. The wood stud wall cavity has been filled with 3-1/2 inch thick fiber glass insulation, one layer of 1/2 inch gypsum board has been mounted to resilient channel spaced 24 inches on center, and the perimeter edge has been sealed. The STC value is 46. The combined effect of absorptive material in the cavity, using 1/2 inch resilient channel to reduce the structural tie between the gypsum board layer and the wood studs, and air sealing the perimeter edge results in increased system acoustical performance.

Sound attenuation blankets are tested per
ASTM C665 Type I and E413

Kenton is right. There is NO substitute for a “sound break”; i.e. non-continuous framing through the wall. Resilient channels are icing on the cake… I was an audio engineer/studio builder in a previous life.


Remember that sound follows air paths. Airseal penetrations between the areas you wish to reduce sound transmission.

One item that Canadian R2000 home owners commented on during contract surveys I did in the late 1980’s was how quiet their new house was from outdoor sounds like cars and wind. One older retrired farmer said he essentially lost his “guard” dog: he had built his airtight, highly insulated, low energy retirement home next door to his 100+ year old family farmhouse. Both homes had about 150 foot long gravel driveways. He claimed when cars had turned into the driveway of the old house, the dog started to bark; with the new house, the dog now barked when people rung the doorbell!!

The first house I owned was ~200 years old Cape cod style post and beam…bought it for $9,500 in 1980…essentially a good wood frame on a hill with a view. It was located in a quite windy area where wind-exposed trees grew with a lean to them. When I finished the airtight energy retrofit (incuding window replacement), the daily regular winds could not be heard; you’d have to look out windows to see if the wind was blowing.

Understanding “flanking sound” is incredibly important!!

True that.
Good article, Brian.