Flanking Noise

Flanking Noise should always be considered when you are planning to upgrade the sound isolation of an existing construction.  This is noise reaching a room via an indirect path. It is important to treat the surfaces on the source side to minimise the amount of vibration which becomes “structure-borne”. Remember, a construction can only perform as good as the level of Flanking Noise.  To achieve further sound isolation the flanking pathways would need to be treated. When sealing around construction types such as timber stud walls make sure you use multiple acoustic sealant layers.  This will ensure a high performing construction due to good sound isolation and sealing. Wall Sockets It is imperative to keep as much of the construction intact from one side of a party divide to the other.  This is ever more important when we look at stud walls with recessed wall sockets.  We would always recommend you follow our simple guideline below to minimise the risk of poor sound isolation.

Never apply the sockets back to back, always apply them in separate cavities.

1. Make sure the sockets are sealed in well
2. Apply insulation around the socket if there is none within the wall construction.  This will help to absorb sound as it travels through and out of the outlet box.
3. Minimize the amount of recessed wall sockets within a party divide.  The more you have, the more likely you are to achieve lower performance values.

 

Recessed Lighting

Recessed lighting has become a style favorite among new build and developments.  This is especially the case in high quality apartments. We would always suggest you recommend our guidelines below when using recessed lighting to reduce the possibility of poor sound isolation.

1. Where possible allow for a sacrificial false ceiling within your overall construction.  This will allow you complete freedom and not affect the sound isolation of the main ceiling construction.
2. If point 1 is not possible then keep the number of lights to a minimum.  The more lights within a dividing party ceiling the higher the likely hood of poor performance.
3. Make sure the lights are fitted with an acoustic hood or a type of light is used with built in hoods.  Be cautious on the suggested performance of these, always follow point 1 and 2 first.

 

What is sound and how does it travel?

Sound is vibrating air.  In order for it to travel form one room to another, sound must first vibrate the inner surface of the wall connecting those rooms.  Then it has to vibrate the surfaces of the next room via the structure of the wall or through the air inside the wall cavity.  Once the surfaces are vibrating on the other side of the wall the new sound is created in the next room.

To achieve good sound isolation we need to impair this process.  Either by impeding the path of the sound once it has vibrated the inner surface of the source room or by giving the wall greater resistance from being vibrated.

5 Principles of Sound Isolation

More and more people are buying bigger, better, and louder TV’s, Stereos and home entertainment systems.  The need for good sound isolation has never been greater and the demand has never been higher.

Sound isolation is not magic its a science.   So if you follow the guidelines below and take in the information we provide then there’s no reason why you cant achieve a good sound isolation with any construction.

1. Mass

Firstly there’s mass.  Mass impedes the transmission of sound in a simple way - its harder for sound to shake a very heavy thing.  If your were to rely solely upon mass for sound reduction then you would need to make very large changes in mass to make large changes in performance.  Typically doubling the mass of a panel without an air cavity will improve the sound isolation by 6dB.

The most common mistake made by many is to add an extra layer of plasterboard to a wall.  Although this shows an improvement without looking and addressing the other principles here there will not be a great deal of improvement.  In fact on a common single stud timber wall, doubling the number of plasterboard layers will yield an improvement of 3-4dB.

2. Mechanical Isolation or De-coupling

Mechanical Isolation is probably the most used method of improving sound isolation but probably one of the least understood.  The most common was to achieve this is using SoundBreaker Bars, staggered studs, double studs, etc.  These are all doing the same thing which is to inhibit the movement of sound from one side of the construction to the other through mechanical paths such as studs or joists.  Creating an air cavity in the wall will ensure the vibration has to pass through it where some of it will be lost.

This method of isolation is frequency dependant.  When you decouple  you create a resonance,  and only above that resonance does it help you.

3. Absorption

Typically sound insulation material in a wall or ceiling cavity will increase the sound isolation by eliminating/removing/destroying some of the sound.  In this situation it can also benefit by lowering the resonant frequency of decoupled walls, less so at very low frequencies.

Absorption won't be much use if you don’t have a decoupled construction however.  In a stud wall for example sound can easily pass through the timber without the need to go through the sound insulation if not decoupling is present.

Work on using the SoundBreaker Bars with the Dense Fibre Matting for best results.

4. Resonance

Resonance makes it easy for sound to vibrate a construction such as a wall.  Even if you took a good, decoupled, insulated wall at a resonant frequency it will still vibrate very easily.  A vibrating wall will vibrate the air on the other side, thus resonance will increase the ease for the sound to be transmitted.

Mechanical Damping can help reduce the magnitude of the resonance and therefore reducing the sound exiting the wall on the other side.  The best method for dealing with this is to apply an visco-elastic layer within the construction to create the damping effect.

This can be achieve by using our NoiseStop Acoustic Sealant between layers of plasterboard for example.

5. Conduction

The last of the 5 principles.  Conduction will stop a non de-coupled construction from attaining a high level of performance.  Conduction plays a big role in Flanking Noise by allowing the solid materials to allow vibrations to transmit directly through unopposed.

To reduce conduction you need to mechanically isolate (discussed in point 2) to separate out the solid masses and/or dampen the structure which will dissipate the energy as it travels through, both ultimately lowering the conduction significantly to a point where its not an important factor.

4 Basic ways to improve sound isolation Increase the mass of the construction Add mechanical isolation if there is none Add absorption if there is none, or increase the level of absorption if some is present Add mechanical damping   Ok, so you understand but you want to know how to apply this to products.  No problem, look below. If we take a traditional stud we can cover the points above using the following: Add an NSSW1+ panel to one side and a double layer of plasterboard to the other. Use SoundBreaker Bars to create the mechanical Isolation.  This only needs to be done to one side. Place Dense Fibre Matting between the studs.  If you use a high density this also improves the mass. Use beads of Acoustic Sealant to isolate the two layers of plasterboard to one side of the stud.

There you go simple.  Now all you need to do is order the products.  Either visit our online shop or call our sales team on 08451 30 62 69.