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Sound is created when air molecules vibrate and move in waves, known as sound waves. As this vibration increases, the sound becomes louder.
Soundproofing is the process of eliminating or reducing these sound waves from travelling between rooms or floors, by using soundproofing material.
There are four main soundproofing methods that are commonly used; decoupling, absorption, damping and mass. Whilst all techniques have their merits and achieve different results, for the best ratings, it is recommended to use all four methods in one assembly.
When there is more contact surface area between two sides of a structure, the vibrations are able to easily travel through and can be heard on the other side. By reducing the contact surface area, the sound waves travel through less areas or pathways and are reduced by the time they reach the other side of the wall or floor.
Decoupling separates the structure (i.e. the drywall from the wall stud or ceiling joists), in order to allow them to vibrate independently from each other, thus creating less sound vibration transfer. Minimal contact significantly reduces sound transmission, and using sound isolation clips, resilient channels, double stud or staggered stud framing are different ways to decouple a wall or ceiling.
One of the most effective decoupling techniques is to use sound isolation clips, which are installed between the stud and furring channel, to disconnect the structure and break up the sound before it reaches the next room. Resilmount® sound isolation clips are the perfect solution for this technique, as the unique sound cell design in the thermoplastic rubber section of the clip absorbs structure-borne vibrations, due to its strong column design that provides a small percentage of contact surface area with the structure or substrate it is fastened to.
Using this simple soundproofing method proves to be highly effective and inexpensive.
Figure 1: Decoupling with Soundproofing Clips
The Absorption method uses a product or assembly to absorb sound waves rather than reflect them.
Fiberglass insulation uses the absorption method by preventing air particles from vibrating and making echoing sounds through a cavity. The air gets trapped between the fibres and turns into heat whilst absorbing sound.
Fiberglass insulation is effective in absorbing some of this reverberation, but density should be kept to a minimum as it should not be compressed or tightly packed in the cavity.
The value of absorption is increased significantly when the assembly is decoupled.
Figure 2: Absorption through fiberglass insulation (photo credit: Soundproofing Company Inc)
Damping is used to disperse vibration energy before it can build up and radiate as sound.
The interior of a wall or ceiling assembly is one way of damping a wall or ceiling and soundproofing a room. The vibration energy is cut off by providing soft, yet tuned, isolation between the source and the structure, thus reducing noise.
Vibration damping is one of the most cost-effective ways to reduce low-frequency structure-borne noise.
Mass involves making the wall structure as heavy as possible. A heavier partition with greater mass is more difficult to vibrate, while a light-weight partition is easy to vibrate, so adding more layers on either side of the wall and increasing the mass in the assembly will let through less sound vibrations.
Adding two layers of 5/8” drywall is one of the most common and cheapest solutions to adding mass to a wall.
Increasing mass will help with low, mid, and high-frequency sound transfer and lead to significant gains in sound isolation.
Figure 3: Mass – Adding layers to the wall (photo credit: Soundproofing Company Inc)
Taking each of these principles into account when soundproofing a room will help to reduce sound transfer, but for maximum performance in your sound isolation project, it is recommended that these techniques are combined in one assembly.
If you would like more information about soundproofing for your project, contact our specialists at [email protected]