How Does Soundproofing Foam Work?

Duncan Geddes

by Duncan Geddes

Some form of soundproofing is the norm for most industrial and domestic buildings. Whether you’re in a restaurant, school or open-plan office, modern buildings are typically designed to control the acoustics architecturally. Either that or they will have soundproofing panels installed to reduce background noise.

Asking how acoustic foam works is usually an invitation for a barrage of jargon and misinformation. That’s why we’ve cut through all the noise to tell you everything you need to know about foam sound insulation and how it works in a way that’s easy to digest.

Soundproofing Foam

The science of sound

Understanding the basic characteristics of sound is vital when you’re exploring how to reduce it. In the very simplest terms, sound is nothing more than the vibration of energy. When an object vibrates, the air around it vibrates too. These vibrations are carried through the air in the form of soundwaves until the air inside your ears begins to vibrate. This sensation is what eventually gets interpreted by the brain as noise, speech and music.

Sound wave


It was soon discovered that certain materials can be used to manipulate how these soundwaves behave. For example, sound energy will naturally bounce off hard surfaces but may become muffled and distorted when coming into contact with soft ones. As such, the science of soundproofing was born.

Absorbing sound vs blocking sound

Before you can understand the workings behind sound insulation foam, it’s important to first establish the difference between absorbing sound and blocking sound. These terms are often used interchangeably, but there are clear distinctions between the two processes.

In the same way as white objects reflect light and black objects absorb it, different materials react to sound in different ways. Various types of acoustic foam can be used either to block out sounds from the outside world or to absorb sounds within a room to reduce reverberations. Therefore, it’s crucial to know what you’re trying to achieve before you invest in any kind of soundproofing solution.

How soundproofing foam works


Sound absorbing foam

Sound absorbing foams are typically softer and more lightweight than their sound blocking counterparts. This open and flexible cell structure acts as a natural soundwave absorber and prevents noises from reverberating off hard surfaces like walls, floors and ceilings. It does this by converting existing sound energy to heat and reducing the ability of soundwaves to bounce back into the room. 

Depending on how it’s used, this type of foam can also enhance the acoustics within a room. Sound absorbing foam cut into pyramid or wedge shapes can be used to manipulate vibrations in a way that improves sound quality. A common example is a recording studio, where echo is reduced through the installation of visible foam tiles and panels on the walls.

Blue soundproofing foam


When to install sound absorbing foam


If you want to absorb sound within a room then you need to soften the hard surfaces. If you’ve ever wondered why ‘cold’ buildings like churches and gymnasiums echo when you clap your hands, it’s because the sound is bouncing off of the walls and ceiling and is then amplified by the shape of the room.

A common approach to soaking up sound within large rooms is to install acoustic tiles that are cut to size and fitted to the biggest surface areas, such as floors and ceilings. This approach can be effective at absorbing airbourne sounds and preventing echo.


Sound blocking foam

The purpose of sound blocking foam is to prevent noise from travelling through walls. This requires materials with the opposite characteristics from the soft, lightweight foam that you’re likely to see in places like recording studios.

Foams with a closer cell structure are therefore more common here, as the thicker and denser the foam, the fewer chances soundwaves have of penetrating through to the other side.

When to install sound blocking foam


If your problem is sound coming through the walls and ceilings from adjoining parts of the building, then you will need to block this sound from getting in.

If you want to block out noise then you will almost certainly need to install sound insulating foam inside the wall construction. These are typically dense, heavy panels that are designed to ‘decouple’ the wall between rooms to stop sounds travelling through materials. Any type of acoustic Basotect foam should have the desired effect, but class O foams are designed specifically for this purpose and comply with existing industry regulations.

Drawing of sound proof design

The future of soundproofing foam

The science behind soundproofing foam is continuously evolving, with new and interesting developments coming out. For example, scientists at the Swiss Federal Institute of Technology in Zurich are currently using theories from quantum mechanics to produce a new material that insulates vibrations rather than allowing them to pass through the foam.

Dubbed ‘super quiet sound proofing’, this new type of material could dramatically reduce the amount of material needed to soundproof a room. Perhaps most exciting of all is that it could allow noise to pass in only one direction – a completely new characteristic with the potential to revolutionise how acoustic foam is used in both commercial and domestic spaces.

Can acoustic foam completely soundproof a room?

For a room to be truly soundproof, the area needs to both absorb sound inside the room and block sound from the outside world. This is a relatively common venture for businesses that need a highly controlled environment, although finding the right balance can be both costly and time-consuming. 

Luckily, we stock a wide range of soundproofing foams and tiles that are ready to be cut and shaped to your specifications. Simply get in touch with one of our expert foam engineers and discover the ideal soundproofing solution for your space.

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