Acoustics
- Does QuietRock deaden sound inside a room, not just keep sound from coming in? A
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QuietRock will reduce the transmission of airborne noise through a wall or floor/ceiling assembly. Reducing sound echo inside a space is a different classification of products aimed at sound absorption. Because QuietRock is a gypsum faced product, it is likely to have the same absorption characteristics as any gypsum drywall panel.
- How do you ventilate (heat and air-conditioning) a room built with QuietRock without undermining the STC performance? A
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Proper design in HVAC is a necessary component to reducing flanking sound transmission from room to room. Generally, main HVAC lines should be along corridors, with supplies and returns branching off of the main line to each unit, according to academic textbooks on this subject.
However, like wall partition design, there are many varied and complex aspects of HVAC design in buildings. We recommend that you consult and collaborate with an acoustical engineer and HVAC professional for design specifics related to HVAC in buildings.
- How is the STC rating calculated? A
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The STC rating is an ASTM standardized metric (ASTM E413) that takes the measured sound isolation data (ASTM E90) and then compares it to a standard contour so the data set (Sound Transmission Loss, or STL) can be classified as a single number. Here is an easier way to compare STC to STL. The STL is simply a set of numbers that are measured with a microphone. It doesn’t mean anything useful until it is correlated to how we experience sound. The STC is meant to take that set of numbers and relate them to how we perceive the reduction in sound transmission through walls. It’s hard to find any meaning in a set of acoustics-related data unless they can relate something to our experience of what things sound like in rooms.
- How will insulating 16″ OC wood wall assemblies with batts affect wall performance? A
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According to a recent research study conducted by PABCO gypsum both fiberglass and mineral wood insulation provided 1-4 STC points of improvement over none at all (empty cavity) even across different treatments that were applied to the wall assembly, such as multiple layers of wallboard, QuietRock in multiple configurations, and soundboard.
When resilient channels are applied to one side of the framing, things change significantly. With resilient channels on the framing, the improvement when adding fiberglass or mineral wool, over no insulation at all, was 7-9 STC points.
There was no statistically significant difference between the fiberglass and the mineral wool insulations in any of these assembly types.
- I am concerned about sound transfer through the duct work. What can your coating do? A
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HVAC ducting represents a potential leakage point for sound transmission from space to space. Our QuietCoat product is designed to damp sound (vibration) in metal surfaces such as sheet metal ducting and can help reduce sound transfer/transmission through these materials. Keep in mind that sound can also travel through the duct opening itself so just using QuietCoat to damp the duct surface may not be enough. We suggest you speak with an experienced HVAC company about products or ways to reduce sound transmission through the duct opening itself.
- If I apply QuietRock panels to both sides of the studded wall will this double the noise reduction? A
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No, unfortunately, acoustical performance is not a linearly additive process. In other words, adding another layer of QuietRock to the opposite side does not result in doubling the noise reduction. Instead, you see an incremental gain in acoustical performance. This incremental gain can vary dependent on the details associated with the assembly design and the materials and components used to construct the wall.
- What is the NRC value of QuietRock? A
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QuietRock is a gypsum drywall faced product and has similar NRC values as other gypsum drywall products.
- What is the relationship between fire and sound? A
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Factors affecting fire resistance and sound control may not always work cooperatively to improve performance. The two major opposing factors are stud spacing and fastener spacing. While narrow stud spacing may improve fire performance, it could decrease sound performance. Likewise, reducing fastener spacing (8” o.c. versus 12” o.c.) on the applied gypsum panels can help improve fire performance while possibly negatively affecting sound performance. Steel stud mil thickness will also inversely affect fire and sound. Where increasing the mil thickness may improved fire performance, it may decrease the acoustic performance; the opposite is also true.
Insulation is a tricky one, while it can improve sound performance, it can have varying effects on fire performance, depending on the assembly.
There are a few steps however that will positively affect both fire and sound, such as, using deeper studs, and increasing the air gap in double framed walls.
- What type of insulation is recommended to boost the acoustical performance of an interior wall? A
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Fiberglass batt insulation is recommended for use with QuietRock. According to our testing on wood framed partitions, there is no statistically significant difference in performance between fiberglass batt and “soundproof” mineral wool insulation.
Resilient batt insulation is recommended over blown-in or spray foam insulations. Blown-in insulation will eventually settle and compact into the bottom of the wall leaving large open air spaces in the upper part of the wall untreated.
According to recent testing by the Gypsum Association, spray foam insulation types such as closed cell or Isocyanate-based foams may decrease the sound isolation of the partition, especially for steel-framed assemblies. Expanding foam creates stiffness with very little additional mass, which is generally detrimental to sound isolation performance.
- When does a room or a partition become soundproof? A
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Soundproof and soundproofing are common words that we use to refer to any material or system that reduces sound inside a room or reduces sound that transmits from room to room. In truth, materials or systems that eliminate all sound (soundproof) don’t exist. Some sound always leaks or transmits through or around partitions and barriers.
- Where can I find PABCO® fire-resistance rated and acoustic designs? A
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Please take a look at these resources:
The Gypsum Association’s GA-600 Fire Resistance and Sound Control Design Manual
UL Product iQ CKNX.R7094 PABCO Gypsum Board
- Would standard pictures and shelving attached to the QuietRock degrade its performance? A
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Unlike “decoupled” approaches such as resilient channel (RC) or sound clip systems (RSIC clips), QuietRock performance is not likely to be affected by attaching shelves, TV’s or other fastened items to the wall. This is because QuietRock technology uses a different approach to attenuating sound.