Sound absorption · Glass wool
SCG Cylence Zoftone
- Thickness
- 25–50 mm
- Density
- 32–64 kg/m³
- Sound absorption (NRC)
- up to 1.00
How to choose sound-absorbing material
In short
First confirm the problem is an echoey room, not sound leaking from elsewhere. Then look at NRC and the absorption values per frequency, especially if the problem sound is low-pitched; check the thickness and test mounting; plan the area and position you will cover; and then choose a facing that suits the use. For fire, moisture and cleaning, check each product's own documents.
1. Is the problem really echo?
Absorbing material fixes reflections inside a room. If the problem is hearing the next room, the fix is in the walls and leaks instead. See Do sound absorbing panels stop noise leaving a room? and Reverberation and reverberation time.
2. Read all the absorption values
- NRC — the average absorption over the speech range (250–2000 Hz); good for a first comparison. See What is NRC
- Absorption per frequency (α) — if the problem is low-pitched, such as music, machinery or a room that booms, also look at 125 and 250 Hz. Two products with the same NRC can absorb bass quite differently
- Other figures you may see — some documents give SAA (ASTM C423) or αw with Class A–E (ISO 11654). These summarise absorption in different ways; don't compare numbers across systems directly
3. Thickness and air gap behind
Absorption depends not only on the material but also on its thickness and mounting.
- Thicker porous material usually absorbs low frequencies better, which is why many manufacturers list NRC by thickness
- An air gap behind the material — mounted on battens or used as a ceiling — usually increases low-frequency absorption
- ASTM E795 defines how specimens are mounted for testing, e.g. laid directly against a surface (Type A) or with an air space (such as E-400). NRC values from these two mountings can't be compared directly
Compare products at the same thickness and the same test mounting, and install them as close as possible to how they were tested.
4. How much, and where
- Area matters — the effect on reverberation depends on the total absorption area (absorption × area). A few panels in a large room may change little
- Ceilings — a large surface rarely blocked by furniture, so a common choice
- Parallel walls — if there is flutter echo between two hard walls, treat at least one of them
- Rooms with defined requirements, such as large meeting rooms or recording rooms, should be calculated by an acoustic consultant
5. Facing and appearance
- Fabric or glass-tissue facings, such as Castle Black Glass Tissue, cover the fibres and give a neat surface
- Ready-made fabric-wrapped wall panels, such as SCG Cylence Zandera and SCG Cylence Zoftone, suit jobs needing both absorption and a decorative finish
- A facing over the material (fabric, perforated foil, paint) can change its absorption. Check whether the published values were measured with that facing, and don't paint over a surface sound must pass through unless the manufacturer says it is fine
- Ducts are a separate case: use duct liners designed for airflow, such as Microfiber PFL or Aeroflex Acoustex, as the HVAC designer specifies
6. Fire, moisture and care — check the datasheet
- Fire behaviour — interior finishes may be subject to building regulations or project requirements; check the test results and standards stated in the documents. See Fire performance terms
- Moisture and location — for humid rooms or semi-outdoor areas, check that the product is suitable
- Cleaning — each facing is cared for differently; follow the manufacturer's instructions
- Installation — use the fixing, adhesive or framing the manufacturer recommends
Don't choose on NRC alone
A higher NRC is not always the better choice. Consider the frequency of the problem, thickness, mounting, installed area and the project's fire requirements together.
See solutions: Echoey rooms · Machine noise
Sources
- ASTM C423 — Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method (NRC, SAA)
- ISO 354 — Measurement of sound absorption in a reverberation room
- ASTM E795 — Standard Practices for Mounting Test Specimens During Sound Absorption Tests
- ISO 11654 — Sound absorbers for use in buildings — Rating of sound absorption (αw, absorption classes)
- ISO 3382-2 — Reverberation time in ordinary rooms
- Manufacturer documents: ROCKWOOL Safe 'n' Silent Pro data sheet, SCG acoustic catalogue (NRC by thickness and mounting)
Related products
Categories and example products for this topic
- SCG Cylence Zoftone — Publishes absorption by frequency; three densities and two thicknesses to compare
- SCG Cylence Zandera — Decorative fabric face in 9 colours where looks matter; NRC 0.75 at 25 mm
- CASTLE Black Glass Tissue — Black 60 g/m² glass tissue to face glass or stone wool behind perforated panels
- M-Board — For rooms with a flat ceiling: glue-on board, NRC 0.53 (Get Best Sound test, unpainted)
Sound absorption · Glass wool
SCG Cylence Zandera
- Thickness
- 25 mm
- Density
- 100 kg/m³
- Sound absorption (NRC)
- 0.75
