What exactly is an absorption class?

To make it easier to compare products from different manufacturers, the PN-EN ISO 11654 standard was introduced. It divides materials into classes based on the Sound Absorption Index (αw).

This index takes a value from 0.00 to 1.00.
Imagine it this way:

• 0.00 is a concrete wall or a mirror – it reflects 100% of the sound that returns to it (creating reverberation).

• 1.00 is an open window – the sound escapes and does not return (it is absorbed 100%).

Classes are simply ranges of this index.

The alphabet of silence - what do the individual letters mean?

Below you will find the class breakdown along with recommendations on where they are best used.

Class A - highest effectiveness (αw = 0.90–1.00)

This is the "heavyweight" in acoustics. Products in this class are highly porous and usually thicker, so they absorb from 90% to 100% of the acoustic energy incident on their surface.

Application: Open spaces, conference rooms, phone booths, recording studios. Anywhere maximum sound reduction and speech intelligibility are the priority.

Example from our offer: EcoBoard 50mm or EcoCloud – these products ensure that noise will be "swallowed".

Class B - very high effectiveness (αw = 0.80–0.85)

Class B products still offer excellent performance. In office practice, the difference between Class A and B is often hard for the human ear to detect, and it may allow greater freedom in choosing finishes (e.g., thinner panels or specific textures).

Application: Offices, corridors, classrooms, libraries.

Classes C, D and E - supporting solutions

Here, the absorption index drops (e.g., Class C is αw 0.60–0.75). Does that mean these products are bad? Absolutely not. They are often materials meant to serve a decorative function, with acoustics as an additional advantage (e.g., thin acoustic wallpapers, carpets, or some furniture).

Application: Home interiors, relaxation zones, where we want to preserve a certain sound "liveliness" rather than achieve a dead studio effect.

Does acoustic panel installation affect the class?

This is a key point for Architects. The same panel can have class C when glued directly to the wall, and class A when installed with an air gap (e.g., on a frame).

This happens because moving the material away from the wall makes the sound wave pass through the panel, reflect off the wall, and pass back through the panel again – so it is filtered twice.

Tip: It is worth checking Nyquista product sheets to see which installation method the absorption class is specified for. Our wall and ceiling panels often achieve much better results with the appropriate installation distance.

Which class should I choose for my project?

Not every room has to be "dead".

1. Do you need silence and focus? (Call center, meeting room) – Aim only for Class A or B. There is no room for compromise here.

2. Do you want to eliminate reverberation in a lobby or corridor? – Class C is often enough, provided you cover a sufficiently large surface area.

3. Are you looking for design? – If you choose, for example, WoodenWall (wooden panels), remember that they combine absorption with reflection (diffusion), which gives a very natural, pleasant sound, even if they do not always have 1.00 αw in the table.

Summary

Choosing an absorption class is a balance between budget, aesthetics, and function. Remember that Class A is the safest choice for offices, but a conscious designer can use the full spectrum of solutions. If you are not sure whether the selected product will fulfill its role in your space, it is worth returning to the topic of acoustic simulations, which will answer this question precisely.