Acoustic Wall Panels — Absorption Classes and Use

Acoustic wall panels absorb sound energy rather than reflecting it, reducing reverberation and improving speech clarity within a room. They are rated by absorption class or NRC, and they do not insulate: they make a room sound clearer but do not stop sound passing through to the next room.

By Dhruv Agarwal · · 1 min read

What it is

Panels designed to absorb sound energy rather than reflect it, reducing reverberation and improving speech clarity within a room.

TypeConstructionTypical use
Fabric wrappedMineral or PET core, fabric faceMeeting rooms, offices
Perforated woodMDF or veneer, perforated, fleece backedBoardrooms, auditoria
PET feltRecycled polyester, mouldedOpen plan, screens, baffles
Baffles and raftsSuspended vertical or horizontalHigh ceilings, open plan
Micro-perforated metalMetal with fine perforationCorridors, durable areas

Specification at a glance

PropertyTypical specification
Absorptionαw class A to E per EN ISO 11654, or NRC
Thickness25mm — 50mm typical
MountingDirect fixed, or on battens with an air gap
CoreMineral wool, glass wool, or PET
Fire classNamed EN 13501-1 class
FacingFabric, veneer, perforated sheet

Specifying it properly

State the absorption class or NRC, the mounting condition including any air gap, the fire class, and the area and placement. A panel's published absorption figure assumes a particular mounting; quoting the figure without the mounting is how a specified class A build-up becomes a class C installation.

Where projects go wrong

  • Panels expected to give privacy. They do not insulate.
  • Mounted flat to the wall when the rating assumed a cavity.
  • Fire class ignored in escape routes and high-occupancy rooms.
  • Placed decoratively rather than at reflection points.
  • Fabric chosen for appearance without checking it is acoustically transparent — a dense fabric over an absorber blocks it.

Standards referenced

Sound absorption rating under EN ISO 11654 and ASTM C423. Reaction-to-fire classification to EN 13501-1.

Standards referenced

  • EN ISO 11654 — Sound absorbers — rating of sound absorption (ISO)
  • ASTM C423 — Sound absorption and sound absorption coefficients (ASTM International)
  • EN 13501-1 — Reaction to fire classification (CEN-CENELEC)

Frequently asked

Absorption reduces reverberation inside a room by soaking up sound energy; insulation stops sound passing between rooms. Acoustic panels do the first, not the second. Adding panels to a meeting room makes it sound clearer and less echoey, but it does nothing to stop conversation being heard next door — that needs partition mass, sealing and careful treatment of the ceiling void.

It depends on the room volume, the surfaces already present and the target reverberation time, but as a working rule 15 to 30 percent of wall area with a high absorption class transforms a hard-surfaced meeting room. Placement matters as much as quantity: panels on first-reflection points and on opposing parallel walls kill flutter echo far more efficiently than the same area spread evenly.

Because absorption at low frequencies depends on panel depth plus the cavity behind it. A 25mm panel mounted tight to the wall absorbs speech frequencies reasonably but does little lower down. The same panel mounted on battens with a 50mm air gap absorbs substantially more at lower frequencies, which is where room boom and HVAC rumble sit. The mounting condition should be specified alongside the panel.

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