What is inside your acoustic panel?

Ever wondered what is inside your acoustic panel? There are three common types of substrate used for the absorption of sound. They are rockwool, fiberglass wool, and Earthwool. Let us take a closer look at the difference between the three and how to choose the substrate best suited for your space.


Also referred as mineral wool, is made from, of course, rocks! Natural rock is heated until melting point, and spun at high speed into rock fibers. It is then compressed into mats of rock wool. Rockwool is a very sustainable material since it contains up to 75 percent recycled content. Other than acoustic treatment, it is also used for insulation due to its ability to retain heat and trap air. It is commonly found in partition walls.

Rockwool is the most durable and long-lasting out of the three options, and does not degrade over time. On top of that, it allows moisture to escape which deters mold to grow over time. Rockwool is one of the most commonly used insulation materials for soundproofing because of its durability and its low cost.

Fiberglass wool

Similar to the production of rock wool, fibreglass wool is made from strands of molten glass. The microscopic fibres are strong yet lightweight. Fibreglass wool comes in two types: soft and rigid. Rigid fibreglass wool is best used in acoustic panels, which gives the panel a firmer touch. Its rigidity provides some resistance at these areas, increasing the longevity of these panels. The binders used in rigid fibreglass wool sometimes gives an acrid smell but should outgas in a week.

Fibreglass wool is also commonly used for thermal insulation and shares the same incombustible properties as rockwool. When exposed to heat, it will not emit smoke or toxic products. In the long run, fibreglass is also a good option because it does not retain moisture and will not attract insects.


Compared to rock wool and fibreglass, earthwool has a much softer texture that is similar to cotton. The density of earth wool is usually very low, at 20kg/m3. Rockwool and fibreglass must be handled with proper protection because the microfibres can penetrate the skin. Earthwool is designed to be easier to handle with its itch-free properties. It is made of 80% recycled glass and sustainable bio-based binder. It also shares the same non-combustible properties and thermal performance as rockwool and fibreglass.

There is also a rigid version of earthwool that provides a firmer touch for use in acoustic panels. But the firm earthwool is a relatively new product, and require more testing to be done before they are commonly available for purchase.

So which "wool" is the best?

Rockwool, fibreglass and earthwool have comparable absorption data. The choice of absorption infill depends on your needs and considerations. If you are looking for the cheapest infill, then rockwool is your choice. If you need something that is rigid and has a “feel good” touch, then rigid fibreglass wool with binders is the correct substrate. If you are looking for something that is more eco-friendly and sustainable, we suggest earthwool is the way to go!