PET vs Melamine Foam vs Wood Wool — Acoustic Material Comparison Guide

Noise in open offices is caused not by the furniture but by sound reflections off hard surfaces. Concrete ceilings, glass partitions, and plywood furniture bounce sound waves repeatedly, creating reverberation.

The solution is to raise the NRC (Noise Reduction Coefficient) using acoustic absorbers to bring the RT60 (Reverberation Time) down to 0.5–0.6 seconds.

Why Office Acoustics Are a Problem

Sound travels as a wave. When it encounters a hard surface it reflects, and reflected sound waves overlap to create reverberation. In a typical office with a concrete ceiling and glass walls, RT60 can easily exceed 1.0 second — well above the speech intelligibility benchmark of 0.5–0.6 seconds.

According to the World Green Building Council report, noise is the number-one complaint in workplace satisfaction, with 99% of respondents saying "office noise reduces concentration." Reduced speech privacy, increased task errors, and accumulated mental fatigue are all connected consequences.

PET Acoustic Panels — The Modern All-Rounder

Recycled PET bottles are the raw material for this non-woven panel. Three plate variants — 9, 12, and 24 mm — are standard; low-frequency absorption improves and NRC rises as thickness increases.

Design variety: Available in a wide range of form factors: wall panels (Basic / V-Design / 3D / Printed / Wavy), ceiling baffles (Linear / Ripple / Curve / Arc / Wing), ceiling clouds (Round / Hexa / Square), desk screens, and acoustic cubes. Compatible with any interior palette across 107 colorways.

Certifications: FITI flame-retardant certification (for 9, 12, and 24 mm respectively), OEKO-TEX Standard 100 (safe for skin contact), and Global GreenTag Platinum (highest environmental impact rating).

Optimal spaces: Open offices, co-working spaces, lobbies, and conference rooms — spaces where acoustic performance and visual design are both required simultaneously.

Melamine Foam — Broadband Absorption and Thermal Resistance

Melamine foam is an open-cell foam based on melamine resin.

Its extremely fine cell structure effectively absorbs sound energy across a broad frequency range; a 50 mm specimen achieves NRC 0.95 (per ASTM C 423 / ISO 354) — the broadband performance of Tornex-processed product based on VIXUM raw material (equivalent to BASF Basotect).

Heat and fire resistance: Service temperature range −200 to +200 °C. Holds 9 certifications across 5 regions including UL 94 V-0, EN 13501-1, DIN 4102-1, and ASTM E84 — a proven material for data centers, hospitals, high-rise buildings, and rail vehicles where fire safety is paramount.

Interior applications: The raw material comes in white and grey as standard. CNC cutting and painting allow it to be applied in modern interiors as flat-finish panels, wave patterns, or wainscoting.

Optimal spaces: Data centers, hospitals, high-rise buildings, rail vehicles, and HVAC rooms — spaces where both fire rating and broadband absorption are simultaneously required.

Wood Wool Boards — Natural Aesthetics and Non-Combustibility

Wood wool board (cement-bonded wood wool) is a rigid panel made by bonding thin wood strands with a cement or magnesite binder. It is a proven material used in European construction for more than 100 years.

Acoustic performance: NRC 0.60–0.85 (depending on thickness, air gap, and installation method). Low-frequency performance (≤ 250 Hz) is moderate, but broadband coverage can be extended by installing with a rear air gap or mineral wool backing.

Design character: An organic texture impossible to replicate with synthetic materials, available in grey, natural, and painted finishes. Well suited to biophilic and warm interior tones. Recyclable thanks to its inorganic binder and natural wood fiber composition.

Optimal spaces: Lobbies, restaurants and cafes, retail, libraries and cultural facilities, and auditoriums — spaces where visual texture is intended to be the finish itself.

Comparing All Three — A Single Summary Table

Absorption Curves by Frequency

A single NRC figure is only an average; the perceived effect varies depending on the actual noise band in the space (low-frequency speech vs. high-frequency sibilance). Octave-band absorption coefficients (α) are compared at equivalent thickness (≈ 25 mm).

Which Is Right for Your Space?

4-Step Selection — Pre-Specification Checklist

Even with a material comparison table and a decision matrix, there are 4 steps that are easy to overlook at the actual specification stage. Working through them in order will help you avoid both under- and over-installation.

Step 1 · Define the Problem — First determine whether the issue is reverberation, speech privacy, or impact noise. Reverberation is addressed with wall and ceiling absorption panels; speech privacy starts with absorption-first installation followed by consideration of sound masking; impact noise is managed with floor carpet tile.

Step 2 · Check Regulations — Korean fire regulations require flame-retardant certification for finish materials above certain area and floor-height thresholds. PET, melamine, and wood wool all have compliant options, but the ratings differ. High-rise buildings, hospitals, and data centers require separate review against EN 13501-1 / UL 94.

Step 3 · Match Design Intent — For modern minimal, use PET (107 colors); for industrial or technical tones, use melamine (paintable); for biophilic or natural tones, use wood wool (the texture itself is the statement). Finish materials are part of the design language, not a separate functional component.

Step 4 · Acoustic Simulation (optional, recommended) — Even with the same NRC value, results can vary by ±20% depending on the finished surface area, layout, and ceiling height. Consult Tornex's technical team or use 3D acoustic simulation to prevent both under- and over-installation.

In Summary

There is no single "best" acoustic absorber. PET excels in design flexibility; melamine in broadband absorption and fire resistance; wood wool in natural texture and non-combustibility — each has a clear strength along a single dimension. The most effective acoustic design often combines two materials: laying broadband absorption across the ceiling while applying a design finish to the walls.

When writing the specification, do not look at NRC figures alone — work through the 4 steps above. For deeper reading, the NRC measurement principles guide and the PET 9T·12T·24T thickness comparison article trace through octave-band curves in full detail.

Seen from Different Perspectives

Related Products and Articles

Product pages — Tornex PET Acoustic Panels · VIXUM Melamine Foam · European Wood Wool Board

Related articles — NRC Measurement Principles · PET 9T·12T·24T Thickness Comparison · Why Melamine Foam Holds 9 Certifications

Frequently Asked Questions

Glossary

• NRC (Noise Reduction Coefficient) — Arithmetic mean of absorption coefficients at four octave bands: 250 / 500 / 1k / 2k Hz. Rounded to the nearest 0.05.
• RT60 (Reverberation Time) — The time (in seconds) for reverberation to decay by 60 dB after the sound source is cut. Recommended for offices: 0.5–0.6 seconds.
• ISO 354 (2003) — International standard for measuring absorption coefficients in a reverberation room. Absorption area is calculated from the difference in reverberation time.
• ASTM C 423 — US standard for measuring sound absorption in a reverberation room. 18 one-third octave bands from 100–5,000 Hz. Basis for NRC calculation.
• KS F 2805 — Korean reverberation room absorption measurement standard. Aligned with ISO 354. Basis for KCL accredited test reports.
• DIN 18041 — German room acoustics design standard (2016). Offices are Group B; A/V (absorption area / room volume) ≥ 0.25.
• EN 13501-1 — European integrated fire classification. A1 / A2 (non-combustible), B / C (limited combustibility), D–F (combustible). Ancillary ratings: s (smoke), d (droplet).
• UL 94 — US plastics flammability rating. V-0 is the most stringent — self-extinguishing within 10 seconds and no flaming drip.
• FITI (Korea Apparel Testing & Research Institute) — Domestic flame-retardant certification testing body. The standard certification under Korean fire regulations (flame retardancy of building finish materials).
• KCL (Korea Conformity Laboratories) — Domestic accredited testing body. Issues KS F 2805 reverberation room measurement test reports.

References

• [1] Noise Reduction Coefficient — Wikipedia (ISO 354 / ASTM C 423 definitions)
• [2] BASF Basotect — Room Acoustics & Design (NRC 0.95, ASTM C 423 / DIN EN ISO 354)
• [3] Mineral bonded wood wool board — Wikipedia (EN 13501-1 A2-s1, d0 rating)
• [4] DIN 18041 — Audibility in rooms (Vital-Office, office RT60 0.5–0.8 s)
• [5] World Green Building Council — Health, Wellbeing & Productivity in Offices (noise #1 complaint, 99% concentration impact)
• [6] Open-Plan Office Noise Increases Stress — research summary (multimodal stress)