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In the vast landscape of architecture and space design, acoustics is often overlooked but of fundamental importance. We will never tire of saying it: the sensory experience of a room is incomplete if the sound that permeates it is not considered.

We have often repeated in our blog that excessive noise and unwanted resonance can disturb your peace of mind and create a stressful and uncomfortable environment. This applies at home and in the office or other public environments.

It is, therefore, crucial to understand how sound-absorbing materials can help improve the acoustics insulation of spaces, creating a more pleasant and balanced sound environment.


How to choose the right sound-absorbing materials: the sound absorption coefficient

Sound absorption, or soundproofing, is how a material reduces sound energy by reflecting, scattering and reducing it. It is of vital importance in architectural structures and interior design.

To reduce reverberation within a room or larger space, the most suitable sound-absorbing materials must be identified. Once the importance of installing such sound-absorbing elements is understood, we move on to the next, slightly more complex phase of choosing these materials and how to install them.

It is necessary to be able to interpret the performance values given in product data sheets in order to make an informed selection. Among these, the sound absorption coefficient cannot be ignored.


Sound absorption coefficient: what is it, and what is it for?

The sound absorption coefficient is an index that measures the ability of a material to absorb sound energy incident on it rather than reflect it.

A high sound absorption coefficient means that the material is able to absorb more sound energy, thus reducing its reflection and contributing to a more comfortable environment free of unwanted noise.

It is calculated using experimental tests in the laboratory, following international standards such as ISO 354:2003 or ASTM C423-19. These tests measure the material’s sound absorption in a reverberation chamber.

The sound absorption coefficient can vary from 0 to 1, where 0 indicates complete sound reflection and 1 indicates complete sound absorption. Sound absorption coefficient values are usually expressed for different frequency bands or specific frequencies to evaluate the acoustic performance of the material over the entire sound spectrum.


Which materials have the highest sound absorption coefficient

Several materials are known to have a high sound absorption coefficient, which means that they can effectively absorb sound. These natural or industrially produced elements have always been used in theatres, recording rooms, offices, schools and private homes.

Let us look at them one by one.


Acoustic melamine foam

This material is widely used in architectural acoustics and sound insulation applications due to its ability to absorb sound effectively. Melamine is a resin that exhibits high porosity and, thus, an excellent ability to retain sound.

Its irregular and porous surface increases sound dispersion, helping to reduce echo and reverberation within a room. Its sound absorption coefficient can vary from 0.6 to 0.95 at medium-high frequencies.

From an environmental point of view, acoustic melamine foam can raise some concerns. Although the raw material is organic and found in nature, producing melamine foam requires resources and energy, and some chemical processes can be polluting if not managed properly.

Furthermore, melamine foam is not biodegradable and can take a long time to degrade if disposed of in landfills.


Stone wool

Stone wool is a sound-absorbing material produced from volcanic or basaltic rocks. Although it is produced using natural resources, the production process requires careful processing and transformation of the rocks, which involves high-temperature processes.

Due to its fibrous properties and mineral composition, the disposal of stone wool may require attention to local environmental regulations. We therefore recommend opting for recycled materials.

Returning to its performance, stone wool is widely used for both acoustic and thermal insulation, as it has a highly porous structure and a sound absorption coefficient between 0.8 and 1.0 at medium-high frequencies.


Plaster and fabric

Traditionally, fabric-covered plaster panels are used in many music venues to make a room more muffled. They can be used to improve room acoustics without sacrificing aesthetics. Their sound absorption coefficient usually varies between 0.6 and 0.9 at medium-high frequencies.

Due to its porous composition and the sheets’ internal structure, gypsum can perform various functions in the control of sound within rooms. Therefore, gypsum plasterboards are used to act as sound absorbers, reflectors or diffusers.

In addition, gypsum acoustic panels are often made of environmentally friendly and recyclable materials, thus contributing to sustainable room design.



Finally, we cannot fail to mention the real protagonist of Diasen’s production, namely cork, used even millennia ago to keep homes warm and quiet.

Cork is a natural and sustainable material with excellent sound-absorbing properties, making it an ideal choice for improving room acoustics. It is obtained from the bark of the cork oak tree, which grows mainly in Mediterranean regions such as Portugal, Spain and Italy. We can therefore count on a reliable and km 0 product.

Its extraction does not damage the oak tree but relies on a peeling process that regenerates the bark.

The sound absorption coefficient of cork is particularly high, thanks to its unique cellular structure In fact, if we look at cork under a microscope, we see cells composed of small air-filled cavities, which act as sound traps, enabling cork to absorb sound waves effectively. This results in a significant reduction in echo and sound reflection within a room.

It is a light, flexible and easily workable material, allowing the creation of sound-absorbing products of different shapes and sizes. It is resistant to moisture and weathering, maintaining its properties over time.

It can be used in various applications, such as sound-absorbing wall and ceiling panels, acoustic floor coverings, subfloors, acoustic insulation panels and more. Its natural, warm aesthetics add a touch of elegance to rooms, making it a popular choice for design and furniture projects.

At Diasen, we produce numerous cork-based products, offering our customers sustainable, affordable and perfectly efficient solutions. Discover, for example, the Diathonite line, biomalts made from environmentally friendly, high-performance materials that are not toxic or harmful to the environment.

For more information on our cork-based acoustic products, don’t hesitate to get in touch with us.

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