A Guide to Wall Soundproofing

Introduction

In this guide, we will give you guidance on how wall soundproofing works. We want to make sure you feel comfortable with the terminology we use, the best course of action to take with intrusive noise issues which can be applicable to all sorts of building types and navigation around our website which will take you to further reading on particular areas regarding soundproofing – this is highly effective in giving you the knowledge to start your path into soundproofing.

A brief explanation of sound

Before we look at wall soundproofing lets learn a little about sound. Sound is made up of a broad spectrum of frequencies which are created by vibrations; when you tap your foot, when you close the door, when you hum a tune – all of these create vibrations that result in the sound you hear and process.

Depending on the frequency of sound the lower the sound is in pitch, the more energy it contains and the more likely it is to travel in all directions and through a range of materials (this could be brick or block work for example)

We have provided a more in-depth description of sound in our ‘A Guide to Sound‘

If we take a 3-way speaker box for example (3 speakers, one above another), we can relate this to how we listen to music. We will help to put it into context with everyday sounds and instruments we may find in these areas and how problematic they can be acoustically

This means that the energy we spoke about, will find it harder to move through dense materials, a brick wall or plasterboard for example.

• 4khz – 20khz (Kilohertz)
• Examples of high frequency;
  • Voice (especially in sibilance which consists of the wooshing and hissing sounds of speech, say the line She Sells Sea Shells by the Sea Shore, lots of sibilance in this example)
  • Drum cymbals, high end of guitar
  • A micro-wave completion tone (the beeps once it has completed)
  • Whistling

• 250hz (Hertz) to 4khz (Kilohertz)
• Examples of middle frequency;
  • Voice can start off at around 250hz
  • Brass instruments
  • Hand percussion
  • Television

An example of this would be hearing a party happening in the distance, you will always hear the thudding of a kick drum or a bass line.

• 20hz -250hz (Hertz)
• Examples of Low Frequency
  • Kick drum
  • Voice (this can be both male and female) creating muffled experience through a wall
  • Impact noise (footsteps, doors closing)
  • Cooker or microwave humming
  • Washing machine or other appliances in operation

You will want to look at the next section as a way of surveying the noise and the path to tackling certain noise issues

How wall soundproofing works

Wall soundproofing works through the physical properties of mass, spring/suspension and absorption, which means that the best acoustic system would have;

A heavyweight to reflect the sound (Mass)

An element of elasticity, spring or (Separation)

 Absorption quality in all adjacent cavities (Absorption)

When reviewing wall soundproofing, it is important to note that noise issues are never completely blocked, the best reduction is when the noise issues reach a background noise level, this is as sound travels in multiple directions and through different parts of your building (see flanking below). You can find a more in-depth discussion on our Science of Soundproofing page, there is also a very handy dB graph here of different noise levels for guidance.

When looking at your wall soundproofing options, you will often see acoustic results which should always be displayed with an acoustic system in place. An acoustic system would always include the partition, this being a stud wall, brick wall, concrete wall and the acoustic soundproofing materials in place – you would not have testing results on an individual product.

One example we come across is direct board options in the region of 45-50dB, please note that this will include the partition – where a heavyweight brick wall may be providing around 40dB of reduction, and the board potentially 5-10dB reduction. We display wherever possible our breakdown of partitions in our performance data.

Another important note is that wall soundproofing materials and systems are relative to the logarithmic scale, which means adding the same system twice, measuring 10dB – would not result in 20dB overall.

A noise checklist

We want to make sure you have everything you need to progress on to the next stage, whether this is deciding to go ahead with the project, to ask iKoustic for a quotation or to place an order – we will help each step of the way.
 

1. Listen to what noises you hear, is it conversation, TV, doors slamming or footsteps for example, or a combination of noises?
2. Are noise issues one of the options below?
   1. Inaudible or background level, so when you are in your room, typical noises mask this noise issue.
   2. Muffled, you can make out there is certainly a noise – but you wouldn’t be able to tell what it is, or what words they are saying.
   3. Clear, you can tell what the noise is and hear words for example, clearly.
3. Are some noises more problematic than others?
4. Is there any Flanking noise? (See next section for a brief description or click on the word Flanking noise)
5. Feel the surfaces, can you feel any vibration coming through?
6. Take notes from anything you notice above, it will help visualise the issue
    

As sound is subjective, what may affect you more than others could be perhaps the slamming of a door, or a washing machine that seems to shake the whole house – but a conversation may not bother you.

Flanking Transmission

Another term you will regularly come across is Flanking (Sound, Transmission, Path) and what this essentially means is that in a wall construction, there will usually be multiple paths that the sound may travel through, below are some examples that could be in your home or workplace.

You can view this under our ‘A Guide to Flanking Transmission’.

We would recommend carrying out a small home test using an open end of a glass to every surface in the room and the base pressed against your ear whilst a sound is being conducted.