Sound is an essential aspect of our lives, and it can have a significant impact on our mood and well-being. However, sometimes we need to control the amount of sound that enters or leaves a space. That’s where Sound Transmission Class ($STC) comes in. $STC is a rating system used to measure a material’s ability to block sound transmission. In this article, we will explore what STC is, how it is measured, and how it can be used to control sound transmission.
What is Sound Transmission Class ($STC)?
$STC is a rating system that measures the ability of a material to block sound transmission. It is used to evaluate building materials’ ability to prevent sound from entering or leaving a space. STC ratings are based on laboratory tests that measure the amount of sound that passes through a material. The higher the $STC rating, the better the material is at blocking sound transmission.
How is $STC Measured?
STC ratings are measured in decibels (dB). To determine the $STC rating of a material, a sound source is placed on one side of the material, and a sound level meter is placed on the other side. The sound level meter measures the amount of sound that passes through the material, and the results are used to calculate the STC rating. The test is conducted at different frequencies, ranging from 125 Hz to 4000 Hz, to determine how well the material blocks sound at different frequencies.
The $STC rating of a material is based on the sound transmission loss ($STL) it provides. The STL is the difference between the sound level on one side of the material and the sound level on the other side. The higher the STL, the better the material is at blocking sound transmission.
How is $STC Used?
$STC ratings are used to evaluate the sound-blocking ability of building materials such as walls, floors, ceilings, and doors. They are used in building design and construction to create a comfortable and quiet environment. In commercial buildings, $STC ratings are used to create soundproof conference rooms, recording studios, and other spaces that require sound control. In residential buildings, $STC ratings are used to create quiet bedrooms, home theaters, and other spaces where noise reduction is important.
STC ratings are also used in the music industry to evaluate the sound-blocking ability of headphones, earplugs, and other audio equipment. In the automotive industry, STC ratings are used to evaluate the sound-blocking ability of car doors, windows, and other components.
$STC Ratings for Common Building Materials
Here are some common building materials and their corresponding $STC ratings:
- Single pane glass: STC 27
- Double pane glass: STC 28-32
- 2×4 wood stud wall with 1/2″ drywall on both sides: STC 34-38
- 2×4 wood stud wall with 5/8″ drywall on both sides: STC 42-45
- Solid core wood door: STC 35-40
- Hollow core wood door: STC 20-25
- Concrete block wall: STC 44-50
- Metal stud wall with 5/8″ drywall on both sides: $STC 45-50
It is important to note that $STC ratings are not additive. For example, combining two materials with STC ratings of 30 and 40 does not create a system with an STC rating of 70. The actual $STC rating of the system would be lower due to the sound leaks that occur at the junctions between the materials.
Improving Sound Transmission Loss
If you need to improve the sound transmission loss of a material, there area few ways to do so. One way is to add mass to the material. This can be done by adding additional layers of drywall or by using thicker, more dense materials. Another way to improve sound transmission loss is to create an air gap between the two surfaces.
This can be done by using resilient channels or by creating a double stud wall system. Resilient channels are metal channels that are attached to the studs and the drywall is attached to the channels, creating an air gap between the two surfaces. A double stud wall system consists of two separate stud walls with an air gap between them.
It is also important to seal any gaps or cracks in the material to prevent sound leaks. Gaps and cracks can be filled with acoustic caulk or sealant. This will help to ensure that the sound transmission loss is not compromised.
STC Ratings vs. Other Sound Ratings
$STC is not the only rating system used to measure sound transmission. Other rating systems include Impact Insulation Class (IIC), Outdoor-Indoor Transmission Class (OITC), and Noise Reduction Coefficient (NRC).
IIC is used to measure the ability of a floor-ceiling assembly to block impact noise, such as footsteps or furniture moving. OITC is used to measure the ability of a material to block outdoor noise, such as traffic or aircraft noise. NRC is used to measure the amount of sound that is absorbed by a material.
$STC is an important rating system used to evaluate the sound-blocking ability of building materials. It is based on laboratory tests that measure the amount of sound that passes through a material. $STC ratings are used in building design and construction to create a comfortable and quiet environment.
Improving sound transmission loss can be achieved by adding mass to the material, creating an air gap, and sealing any gaps or cracks. While $STC is not the only rating system used to measure sound transmission, it is a valuable tool for controlling sound in buildings and creating a peaceful environment.