Three material families dominate the sound-absorbing market: PET acoustic panels, wood wool board, and melamine foam. Each has distinct advantages, and the optimal choice depends on space type and acoustic objectives.
The Three Core Absorptive Materials
PET Acoustic Panels
Polyester fiber · Lightweight · 107 colors
Wood Wool Board
Wood fiber + cement · Natural texture
Melamine Foam
Ultra-lightweight · Broadband absorption · Cost-effective
NRC Absorption Performance Comparison
- Material: Melamine foam 50T · NRC: 0.95
- Material: PET 24T · NRC: 0.90
- Material: PET 12T · NRC: 0.84
- Material: PET 9T · NRC: 0.79
- Material: Wood wool board 35T · NRC: 0.75
NRC by material and thickness
◆ = best in class. Reverberation room method (KS F 2805 / ISO 354).
Frequency-Band Absorption Characteristics — DIN 18041 Perspective
NRC is simply an averaged value. To assess DIN 18041 compliance, per-band performance across 250–2,000 Hz matters. Each material has its own absorption profile:
Want to understand the difference between sound isolation and sound absorption first? See the fundamentals guide: Soundproofing vs. Sound Absorption.
PET Acoustic PanelRecycled PET fiber · mid-high freq specialist
Polyester fiber, lightweight, 107 colorways — design freedom and acoustic performance combined.
At 12mm, 250 Hz α = 0.62 meets DIN 18041 Group B4. At 24mm, the absorption profile extends to 400 Hz (α ≥ 0.85), suitable for Group A3–A4 meeting rooms.
PET Panels — Mid- and High-Frequency Specialists
PET panels excel above 500 Hz; at 1,000 Hz and above, the absorption coefficient exceeds 1.0. At 12T, the 250 Hz absorption coefficient is 0.62, meeting DIN 18041 Group B4 office requirements.
At 24T, the absorption profile extends down to 400 Hz (α ≥ 0.85), making it suitable for Group A3–A4 meeting rooms as well. Key advantage: the only material that combines performance and design flexibility across 107 custom colors.
Curious about absorption coefficient differences by thickness? Explore the detailed PET acoustic panel comparison by thickness (9T · 12T · 24T).
Wood Wool BoardWood fiber + cement · mid-freq anchor
Wood fiber bonded with cement. Stable mid-freq (500–1,000 Hz) absorption with natural texture, preferred for exposed ceilings, halls, and lobbies.
At 35mm, NRC 0.75 — lower than PET but featuring Class A2 fire rating and exceptional durability, meeting DIN 18041 Group A spec for halls and lobbies.
Wood Wool Board — Mid-Frequency Anchor
Wood wool board delivers stable, broad absorption centered on the mid-frequency range (500–1,000 Hz). Its cement-based construction earns a quasi-noncombustible rating (under Korean standards) and is highly durable. At 35T, NRC 0.75 is lower than PET, but its natural texture and visual warmth make it the preferred choice for exposed ceiling designs in lobbies, restaurants, and auditoriums.
Melamine Foam (VIXUM)Ultralight · broadband absorption
50mm NRC 0.95. α ≥ 0.90 across 1,000–4,000 Hz; with 75 mm rear air gap, 250 Hz α rises to ~0.65–0.75 for broadband absorption.
At ~1.6 kg/㎡ (50mm), the lightest of the three. Air-gap installation using ceiling plenum is standard, suitable for offices and studios requiring broadband absorption.
Melamine Foam — Ultra-Lightweight Broadband Absorber
At 50T, NRC 0.95 — delivering excellent absorption above 500 Hz (α ≥ 0.90 from 1,000–4,000 Hz).
Direct-mount absorption at 250 Hz is moderate (0.20–0.50), but adding a 75 mm air gap behind the panel significantly improves mid- and low-frequency performance — raising 250 Hz absorption to approximately 0.65–0.75, rivaling thicker panel systems.
At 50T, approximately 1.6 kg/m² — the lightest of the three materials. Installed with an air gap (standard practice for ceiling applications), it delivers broadband absorption suitable for both offices and studios.
Air Gap Effect — The Hidden Performance Multiplier
An air gap is the empty space between the absorptive material and the wall or ceiling surface. Placing a 75 mm air gap behind a 50 mm melamine foam panel creates a total acoustic depth of 125 mm, substantially improving low- and mid-frequency absorption.
- Frequency: 250 Hz · 50T direct-mount: 0.20 · 50T + 75 mm air gap (estimated): 0.65–0.75 · Improvement: ▲ +225%
- Frequency: 500 Hz · 50T direct-mount: 0.55 · 50T + 75 mm air gap (estimated): 0.90–0.95 · Improvement: ▲ +70%
- Frequency: 1,000 Hz · 50T direct-mount: 0.90 · 50T + 75 mm air gap (estimated): 0.95–1.00 · Improvement: ▲ +8%
- Frequency: 2,000 Hz · 50T direct-mount: 1.00 · 50T + 75 mm air gap (estimated): 1.00 · Improvement: —
- Frequency: 4,000 Hz · 50T direct-mount: 0.92 · 50T + 75 mm air gap (estimated): 0.95 · Improvement: ▲ +3%
* Direct-mount data: Sound Service UK / SINOYQX published specifications. Air gap estimates are based on acoustic engineering principles — an air gap increases the effective acoustic depth and shifts the absorption curve toward lower frequencies.
In practice, ceiling-mounted melamine foam almost always includes an air gap (the plenum space above the ceiling grid). Therefore, "with air gap" data more accurately reflects real-world installed performance.
PET wins on color and customization, wood wool on natural texture, melamine on absorption-per-weight — there is no single winner.
Full Comparison Table
- Item: NRC (representative value) · PET acoustic panel: 0.84 (12T) · Wood wool board: 0.75 (35T) · Melamine foam: 0.95 (50T)
- Item: Frequency strength · PET acoustic panel: Mid/high (500 Hz+) · Wood wool board: Mid (500–1,000 Hz) · Melamine foam: Broadband (500 Hz+; 250 Hz+ with air gap)
- Item: Fire rating · PET acoustic panel: Flame-retardant · Wood wool board: Quasi-noncombustible · Melamine foam: Flame-retardant (domestic) / Quasi-noncombustible (international)
- Item: Weight (per m²) · PET acoustic panel: 2.4 kg · Wood wool board: 12 kg · Melamine foam: ~1.6 kg
- Item: Color options · PET acoustic panel: 107 custom colors · Wood wool board: Natural tones (5 options) · Melamine foam: White/Grey
- Item: Texture · PET acoustic panel: Felt/fabric · Wood wool board: Natural wood grain · Melamine foam: Sponge-like
- Item: Durability · PET acoustic panel: High · Wood wool board: Very high · Melamine foam: Moderate
- Item: Installation · PET acoustic panel: Easy (adhesive/clip) · Wood wool board: Requires specialist · Melamine foam: Very easy
- Item: DIN 18041 compliance · PET acoustic panel: Group B4 (office) / A3–A4 (24T) · Wood wool board: Group A (auditorium, lobby) · Melamine foam: Group B4 (office, with air gap) / B3
PET vs Wood Wool vs Melamine — 8 axes
◆ marks best-in-class. Visualized from full body comparison.
| 기준 | PET 흡음패널 | 목모보드 | 멜라민폼 |
|---|---|---|---|
| NRC (typical) | |||
| Frequency strength | Mid-high (500 Hz+) | Mid (500–1k Hz) | Broadband (with gap) |
| Fire rating | Class B | Class A2 | Class B (KOR) / A2 (INT) |
| Weight (per ㎡) | 2.4 kg (12mm) | 12 kg | 1.6 kg (50mm) |
| Design freedom | 107 colors · in-house CNC | 5 natural · paintable | White/Gray |
| Installability | Easy (adhesive/clip) | Specialist required | Very easy |
DIN 18041 A/V Ratio — How Much Do You Need?
DIN 18041 Group B spaces determine the required acoustic treatment quantity via the A/V ratio (equivalent absorption area / room volume). Requirements by space type are as follows:
B3 — Canteen and Laboratory (A/V ≥ 0.20)
Spaces with moderate occupancy duration. A 100 m³ space requires at least 20 m² of equivalent absorption area. Melamine foam 50T ceiling (with air gap) or PET 9T partitions are effective.
PET 9T / Melamine foam
B4 — Office (A/V ≥ 0.25)
Noise reduction and comfort for full-day occupancy. A 150 m³ office requires at least 37.5 m² of equivalent absorption area. Applying PET 12T panels to 40% of wall area is the standard solution.
PET 12T recommended
B5 — Call Center (A/V ≥ 0.30)
Spaces requiring maximum noise reduction. Both walls and ceilings require treatment. The proven solution is PET 12T on walls combined with melamine foam on the ceiling.
PET 12T + melamine foam combination
Group A3/A4 — Meeting Rooms
Reverberation time control for speech intelligibility. PET 24T or wood wool board provides the mid-frequency absorption needed to achieve the target T value.
PET 24T / Wood wool board
Material recommendation by space type
Office (Group B4)
150㎥ · A/V ≥ 0.25 · all-day work
Educational / Meeting (Group A3–A4)
RT control · intelligibility priority
Call center (Group B5)
A/V ≥ 0.30 · max noise reduction
Studio / recording
RT60 < 0.3s · full-band control
Hall / Lobby (Group A)
Exposed ceiling · natural texture
Restaurant / Lab (Group B3)
100㎥ · A/V ≥ 0.20 · medium stay
Recommended Combinations by Space Type
Office
PET 12T on walls combined with carpet tile flooring is the most common combination. With 107 colors available, you can select a shade to match your corporate identity.
PET 12T recommended
Educational Facilities
PET 24T or wood wool board for reverberation control across large areas. As a multi-user facility, fire-retardant certification documentation is mandatory.
PET 24T / Wood wool board
Recording Studios
Melamine foam 50T with air gap (broadband) combined with PET 24T (mid/low frequencies) covers the full frequency range. Correct placement of reflective surfaces is central to proper acoustic design.
Melamine foam + PET 24T
Restaurant / Café
In dining spaces, both aesthetics and acoustics matter. All three materials offer their own advantages; the choice depends on ceiling structure and design intent.
PET Panel
When aesthetics are a priority in dining spaces — PET is widely used for its design flexibility. Available in 107 colors and a variety of pattern options.
Design-led choice
Wood Wool Board
Its distinctive natural texture is the key advantage. Can be painted in the full Pantone range for a custom finish that integrates with any interior.
Natural texture choice
Melamine Foam
No ceiling depth constraints — viable at 100T and beyond. Optimal for exposed ceilings where mid/low-frequency absorption is needed. Ultra-lightweight (safe in the event of detachment), internationally rated quasi-noncombustible.
First choice for exposed ceilings
PET / Wood wool board / Melamine foam — selected according to design intent
Frequently Asked Questions
Q1Can different absorbers be mixed in one space?
Q2Do all three materials carry fire-resistance certification?
Q3How do I calculate the required absorber quantity?
The Formula Is a Starting Point — Not the Conclusion
The A/V ratio calculations above provide a reliable baseline, but actual acoustic requirements vary significantly with space type, occupancy, ceiling height, furniture density, and real-world usage patterns. Two spaces of identical floor area can perform very differently in acoustic terms.
Tornex conducts 3D acoustic simulation before installation and uses auralization so clients can hear how the treated space will sound before any panels are installed. Post-installation RT60 measurement on-site confirms the results. This pre- and post-installation verification is what distinguishes a professional acoustic solution from guesswork.
When selecting an acoustic consultant, choose a firm that provides both pre-installation simulation and post-installation measurement — not merely a product supplier.
Find the Right Acoustic Solution for Your Space
Tornex is a comprehensive acoustic solutions partner — offering PET panels, wood wool board, and melamine foam all from a single source.
View PET Acoustic Panels →
View Wood Wool Board →
View Melamine Foam →
Glossary
- NRC (Noise Reduction Coefficient) — Average of 1/3-octave absorption coefficients at 250, 500, 1,000, and 2,000 Hz, rounded to the nearest 0.05. ASTM C423.
- αw (Weighted Absorption Coefficient) — Single-number rating per ISO 11654. Derived by fitting a reference curve to the measured curve; value read at 500 Hz.
- Absorption Class A–E — ISO 11654 αw-based classification. Class A (αw ≥ 0.90) = highest performance. Melamine foam 50T with air gap falls in the Class A range.
- ISO 354 — Standard for measuring sound absorption in a reverberation room. Equivalent absorption area calculated via the Sabine equation. KS F 2805 is the equivalent Korean standard.
- KS F 2805 — Korean Industrial Standard for sound absorption measurement by the reverberation room method. Equivalent to ISO 354. Basis for KCL and FITI test certificates.
- DIN 18041:2016 — German indoor acoustic standard. Group A (auditoriums, classrooms up to 5,000 m³) / Group B (offices, canteens, short-distance communication). Minimum equivalent absorption area defined by A/V ratio.
- A/V Ratio — Equivalent absorption area A (m²) ÷ room volume V (m³). Recommended: Group B4 (office) ≥ 0.25, B5 (call center) ≥ 0.30.
- RT60 (Reverberation Time) — Time for sound pressure to decay 60 dB after a sound source is cut off. Recommended: studio < 0.3 s, office 0.5–0.8 s.
- EN 13501-1 — EU unified fire classification for construction products. A1 (non-combustible) · A2 (limited combustibility) · B (flame-retardant) · C–F. Wood wool = A2, melamine foam = A2 / B.
- E400 Mounting — Test mounting code per ASTM E795. 400 mm air gap behind test specimen simulates ceiling grid installation. Enhances low-frequency absorption.
References
The standards, test criteria, and material data cited in this article can be verified against the following primary sources.
- ISO 354:2003 — Acoustics — Measurement of sound absorption in a reverberation room
- ISO 11654:1997 — Sound absorbers for use in buildings (αw, Class A–E)
- DIN 18041:2016 — Acoustic quality in rooms (Group A/B classification)
- KS F 2805 — Sound absorption measurement by reverberation room method (Korean Industrial Standard)
- Noise Reduction Coefficient (NRC) — ASTM C423 definition (Wikipedia)
- Basotect (melamine foam) — BASF Brochure: Room Acoustics and Design
- Heraklith (wood wool board) — Knauf Insulation Noise Absorption