Exploring sound absorption

Understanding how sound absorption works and what helps you absorb sound.

Sound waves always fade away.

Sounds don't last forever. However, they don't always disappear as quickly as we hoped. The trick to absorb sound is preventing it from being reflected and extended.

To do just that, we'll need absorption

Absorbing materials help you speed up the process

Sound waves have to travel through something. Some materials remove the sound energy when it travels through them, just like sponges absorb water. Other materials reflect it, like mirrors reflecting light.

Sound absorbing materials trap sound waves and convert them into heat energy, elliminating sounds.

They're especially good at reducing reverberation times.

(What are reverberations?)

What spaces have long reverberation times?

Sports halls



Lecture theaters

Cinemas and theaters

Sound absorption can be applied in many ways

Generally, you can apply absorving materials to floors, walls, ceilings, partition surfaces and any item in the room! The use of sound absorbing screens is also becoming more common.

When should you use sound absorption?

When reverberation times are too long.

When you can't understand what's being said ( low speech intelligibility).

Reduce noises from the same room.

Reducing echoes and reverberations.

Cinemas and theaters

What type of absorbers are there?

Porous absorvents

Porous absorvents are usually materials with some form of holes that trap and absorb sound.
Sound waves travel through this material and, when they're trapped, they're converted into heat energy.

The conversion of sound waves into heat energy results in the sound effectively being absorbed.

In some absorbers with open surfaces, the air movement resulting from sound waves pushes air particles through the narrow passages which in turn generate a viscous loss along with heat.

Resonance absorvents

Perforated materials that trap sound energy in holes or slots of different depths where it is then converted into oscillation energy. Resonators can be customised to reduce a specific set of frequencies. Examples: perforated wood, metal and gypsum board.

Absorption changes in different frequencies

Low frequency sounds, below 500 Hz, tend to be more difficult to absorb whereas high frequencies sounds, above 500 Hz, are easier to absorb.

The sound absorbing coefficient tells you how good the material is at absorbing sound at different frequencies. It's value, alpha, ranges from 0 (non-absorvent) to 1 (very absorvent)

Talking rooms need a bit more attention

A meeting room is a place where everyone needs to understand what is being said. That doesn't happen if the people in the back can't hear. That's when you need a mix of diffusion and absorption.

In places where speech intelligibility is important, you'll want to have absorption to prevent direct reflections, but also diffusion, so that sound waves can be carried to the back evenly.


Ready to de-stress after a long day?
See some absorbing panels here.