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Sound and acoustics

Do sound absorbing panels (high-NRC materials) stop sound leaving a room?

5 min read · Written by our team · Updated 26 Sept 2026

Two rooms divided by a thin wall: the first has a speaker and acoustic panels, yet red sound arcs still pass through the wall into the next room with an armchair.
In short

Only very slightly. Absorption panels and materials with a high NRC are designed to reduce reflections inside a room, not to stop sound passing through a wall. They are light and porous, so air — and most of the sound — goes straight through. To keep sound from reaching the next room you have to work on the walls, ceiling, floor, doors and air leaks as a system.

Comparison diagram: on the left, sound insulation — less sound passes through the complete wall to the next room; on the right, sound absorption — the absorbing panel reduces reflections inside the room, but some sound still passes through the wallSound insulation 12Sound absorption 345 Comparison diagram: on the left, sound insulation — less sound passes through the complete wall to the next room; on the right, sound absorption — the absorbing panel reduces reflections inside the room, but some sound still passes through the wallSound insulation 12Sound absorption 345
  1. 1The complete wall: linings, cavity, cavity insulation and sealed gaps work together
  2. 2Less sound reaches the next room — rated with the STC / Rw of the whole wall
  3. 3An absorbing panel on the wall takes up part of the sound energy — rated with NRC
  4. 4Less sound is reflected back, so the room echoes less
  5. 5Some sound still passes through the wall — an absorbing panel is not sound insulation

Which problem do you have?

Sound coming in from outside, or going out of your room You need sound insulation Fix sound through walls Echo, reflections, speech hard to understand You need sound absorption Fix an echoey room

Absorption panels make a room less echoey, but they do not stop sound passing through a wall

Why can the neighbours still hear after panels go up?

Sound gets from one room to another in two main ways:

  • Through the wall itself — sound makes the wall vibrate, and the far side radiates sound again
  • Through gaps and indirect paths — gaps under doors, around frames, electrical outlets, the space above a suspended ceiling, ducts and continuous structure

Panels fixed to the wall surface do not make the wall meaningfully heavier or more airtight, and they do not close these indirect paths. Most of the sound still gets through.

How absorption and insulation differ

Absorbing materialSound-insulating system
---------
JobReduce reflections in the roomReduce sound passing to another room
CharacterLight, porous, lets air throughHas mass, airtight, better if the two sides are decoupled
RatingNRC (of the material)STC / Rw (of the whole wall)

More in Sound insulation vs sound absorption, What is NRC and What are STC and Rw.

So what do absorption panels help with?

  • Less echo and reverberation, clearer speech — see Reverberation and reverberation time
  • Less build-up of reflected sound inside a noisy room, so that room itself feels somewhat less loud. The effect on sound reaching other rooms is limited, and it does not make up for a weak wall or air leaks
  • Used as cavity insulation inside a wall, glass wool or stone wool becomes part of a sound-insulating system — a different role from panels on the surface. See Why cavity insulation improves a wall's sound insulation

Foam or panels on the wall do not make a soundproof room

Covering walls with wedge foam or absorption panels makes a room less echoey, but it does not make it soundproof. If the goal is to stop disturbing the neighbours, start by checking the walls, doors and air leaks.

What to do if you need to keep sound in

  1. Seal leaks first — under doors, around frames, wall-to-floor and wall-to-ceiling joints, outlets cut through the wall
  2. Look for indirect paths — walls that stop at the suspended ceiling, ducts serving both rooms. See Sound transmission and flanking
  3. Upgrade the wall as a system — heavier boards, decoupled framing, cavity insulation, installed to the system the manufacturer tested or specifies
  4. Add absorption as well if the room is still echoey, so sound inside is clearer

Results depend on the whole system and the site; no single material guarantees a sound insulation result. Send us your wall design and a description of the problem and we can help.

See solutions: Noise from next door / neighbours · Echoey rooms

Sources

  • ROCKWOOL International — 5 facts about Acoustics and stone wool (2020): definitions of sound absorption and sound transmission loss
  • National Research Council Canada — Construction Technology Update No. 66, Airborne Sound Insulation in Multi-Family Buildings (Quirt & Nightingale, 2008)
  • National Research Council Canada — Construction Technology Update No. 1, Control of Sound Transmission through Gypsum Board Walls (Warnock & Quirt, 1997)
  • ASTM C423 / ISO 354 — measurement of sound absorption in a reverberation room (basis of NRC and absorption coefficients)
  • ASTM E413 / ISO 717-1 — rating of sound insulation, STC / Rw

Related products

Categories and example products for this topic

Sound absorptionSound insulation
  • SCG Cylence Zoftone — Wall absorption panel: reduces echo in the room but does not stop sound through walls
  • Top Tone — Acoustic foam: cuts echo in the room but cannot stop sound through walls - add drywall
  • ROCKWOOL Safe 'n' Silent Pro — To keep sound in: stone wool for drywall cavities, as one part of the wall system
  • SCG Cylence ZoundBlock — To keep sound in: glass wool for wall cavities; SCG publishes wall systems using it
See related products Help me choose

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