Sound insulation vs sound absorption

Q: 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

Q: Is stone wool in a wall insulation or absorption?

Stone or glass wool in a wall cavity is part of a sound-insulating system . The insulation absorbs sound inside the cavity, but the insulation performance comes from the whole wall together: boards, framing, infill and sealing.

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

Two adjoining rooms in section: in one, red sound arcs from a speaker travel toward a thick dividing wall; in the other, the sound fades among panels on the wall and ceiling.

In short

Sound insulation reduces the sound travelling through walls, ceilings or floors from one room to another. Sound absorption reduces the reflections inside a room. They use different materials and methods. Absorption panels make a room less echoey, but they do not block noise from the room next door.

1The complete wall: linings, cavity, cavity insulation and sealed gaps work together
2Less sound reaches the next room — rated with the STC / Rw of the whole wall
3An absorbing panel on the wall takes up part of the sound energy — rated with NRC
4Less sound is reflected back, so the room echoes less
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

Sound insulation: less sound between rooms

Sound passes through a wall because the wall vibrates with it, and because of gaps. Sound insulation relies on:

Mass — heavier boards are harder to set vibrating
Decoupling — two leaves that are not rigidly connected pass less sound
Cavity insulation — reduces resonance inside the wall
Sealing — small gaps let a lot of sound through

It is rated with STC or Rw, which describe the whole wall system. More in What is STC?

Sound absorption: fewer reflections in the room

Porous or fibrous materials, such as absorption panels and open-cell foam, turn part of the sound energy into a tiny amount of heat, so less sound reflects back into the room. The room rings less and speech is clearer.

It is rated with the material's NRC. More in What is NRC?

Side by side

	Sound insulation	Sound absorption
---	---	---
Solves	Noise from other rooms or outside	Echo, reflections, unclear speech
Works at	Walls, ceilings, floors, doors, windows	Surfaces inside the room
Relies on	Mass, decoupling, sealing	Porous or fibrous materials
Rating	STC / Rw (whole system)	NRC (material)
Typical use	Walls between bedrooms, plant rooms	Meeting rooms, restaurants, halls

Is stone wool in a wall insulation or absorption?

Stone or glass wool in a wall cavity is part of a sound-insulating system. The insulation absorbs sound inside the cavity, but the insulation performance comes from the whole wall together: boards, framing, infill and sealing.