Sound absorption classes (A, B, C...) – what do they mean and how do they affect the choice of panels?

What is the absorption class?

To facilitate the comparison of products from different manufacturers, the standard PN-EN ISO 11654 was introduced. It divides materials into classes based on the Sound Absorption Index (αw).

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

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

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

Classes are simply ranges of this index.

Silence Alphabet - what do the individual letters mean?

Below you will find a classification of classes along with recommendations on where to best use them.

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

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

Applications: Open spaces, conference rooms, phone booths, recording studios. Anywhere maximum soundproofing and speech intelligibility are prioritized.

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

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

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

Applications: Offices, corridors, classrooms, libraries.

Classes C, D, and E - supporting solutions

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

Applications: Home rooms, relaxation areas, where we want to maintain a certain "liveliness" of sound rather than achieve the effect of a dead studio.

Does the installation of acoustic panels affect the class?

This is a key point for architects. The same panel may 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 causes the sound wave to pass through the panel, reflect off the wall, and return through the panel again – thus it is filtered twice.

Tip: It is worth checking the Nyquista product sheets to see what installation method the absorption class is given for. Often, our wall and ceiling panels achieve significantly better results with the right installation distance.

What class should I choose for my project?

Not every room needs to be "dead".

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

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

3. Are you looking for design? – If you choose, for example, WoodenWall (wood panels), remember that they combine absorption with reflection (diffusion), creating a very natural, pleasant sound, even if the table does not always show 1.00 αw.

Summary

The choice of absorption class is a balancing act between budget, aesthetics, and function. Remember that class A is the safest choice for offices, but a conscious designer can leverage the full spectrum of solutions. If you are unsure whether the chosen product will fulfill its role in your space – it is worth revisiting the topic of acoustic simulations, which will answer this question precisely.