Acoustic Panel Materials Compared
DIY · 11 min read · ResonAia Editorial
Compare the performance, cost, and applications of common acoustic materials. Make informed choices for your absorption and treatment projects.
Understanding Acoustic Materials
Acoustic absorbers work by converting sound energy to heat through friction as air molecules move through fibrous or porous materials. The key properties determining performance are:
- Density: Affects absorption coefficient at different frequencies
- Thickness: Determines low-frequency cutoff
- Flow resistivity: Controls how easily air passes through
Let's compare the common options.
A note on these numbers: Published absorption numbers are test-condition dependent. Treat the values below as planning examples only — always check manufacturer data for thickness, mounting type, air gap, density, facing, and test standard before specifying a real installation. You'll also see NRC and per-frequency coefficients at or above 1.00 in a few tables below (rigid fiberglass and rockwool, in particular): that's not physically-impossible "over 100% absorption," it's an apparent coefficient from the reverberation-room test method. ASTM C423 itself cautions that these are operationally-defined values, and diffraction/edge effects at the sample boundary can push the calculated coefficient slightly above 1.0.
Rigid Fiberglass (Owens Corning 703/705)
Properties
- Density: 3-6 lb/ft³ (48-96 kg/m³)
- Typical thickness: 2-6 inches
- NRC Rating: 0.95-1.05 at 4" (values ≥1.0 are apparent coefficients from the reverberation-room method, not >100% physical absorption — see note above)
- Cost: $15-25 per 2'x4' panel (2")
Performance
One of the most widely used materials for acoustic absorption. Excellent broadband performance with high absorption across mid and high frequencies. At 4"+ thickness, effective down to ~125 Hz.
| Thickness | Absorption Coefficient by Frequency |
|---|
| 2" | 125Hz: 0.22, 500Hz: 1.00, 2000Hz: 1.00 |
| 4" | 125Hz: 0.84, 500Hz: 1.00, 2000Hz: 1.00 |
| 6" | 125Hz: 1.00, 500Hz: 1.00, 2000Hz: 1.00 |
Best For
- Studio broadband absorbers
- Bass trapping (6"+)
- First reflection panels
- Professional installations
Limitations
- Requires enclosure (fabric, plastic, etc.)
- Handling requires protection (fibers are irritating)
- Not structural
Rockwool / Mineral Wool (Roxul/Rockwool)
Properties
- Density: 4-8 lb/ft³ (64-128 kg/m³)
- Typical thickness: 2-6 inches
- NRC Rating: 0.95-1.05 at 4" (apparent coefficient — see note above)
- Cost: $10-20 per 2'x4' panel (2")
Performance
Nearly identical to rigid fiberglass for absorption. Slight density advantage at some frequencies. Often preferred for DIY due to easier handling (less irritating) and lower cost.
Absorption coefficients virtually match OC 703/705 at equivalent densities.
Best For
- DIY absorbers and bass traps
- Budget-conscious installations
- Applications where fiberglass irritation is a concern
- Fire-rated assemblies (excellent fire resistance)
Limitations
- Slightly less rigid than fiberglass (may need more support)
- Dust during cutting (use mask)
- Heavy when dense
Acoustic Foam
Properties
- Density: 1-2 lb/ft³ (16-32 kg/m³)
- Typical thickness: 1-4 inches
- NRC Rating: 0.3-0.8 depending on thickness
- Cost: $5-15 per square foot
Performance
Significantly lower absorption than fibrous materials. Effective only at mid-high frequencies. Thin foam (1-2") has minimal effect below 500 Hz.
| Thickness | Absorption Coefficient by Frequency |
|---|
| 1" | 125Hz: 0.05, 500Hz: 0.35, 2000Hz: 0.90 |
| 2" | 125Hz: 0.10, 500Hz: 0.65, 2000Hz: 0.95 |
| 4" | 125Hz: 0.25, 500Hz: 0.95, 2000Hz: 0.90 |
Best For
- High-frequency absorption only
- Decorative applications
- Voice-over booths (supplementing other treatment)
- Treating specific HF problems
Limitations
- Poor low-frequency performance
- Degrades in sunlight
- Fire hazard (use only fire-rated products)
- Often overused/misapplied in studios
Compressed Cellulose (Cellulose Fiber)
Properties
- Density: 3-4 lb/ft³
- Typical thickness: 2-4 inches
- NRC Rating: 0.80-0.95 at 3"
- Cost: $20-30 per 2'x4' panel
Performance
Good absorption, between foam and fiberglass. More environmentally friendly than mineral options. Often used in commercial acoustic panels.
Best For
- Commercial and architectural installations
- Green building projects
- Applications where sustainability matters
Limitations
- Less effective than fiberglass at equivalent thickness
- Can absorb moisture (needs protection in humid environments)
- Less common, harder to source
Cotton / Recycled Denim
Properties
- Density: 2-3 lb/ft³
- Typical thickness: 3-4 inches
- NRC Rating: 0.75-0.90 at 3"
- Cost: $15-25 per 2'x4' panel
Performance
Moderate absorption, similar to cellulose. Non-irritating, safe to handle without protection. Often marketed as "eco-friendly" alternative.
Best For
- DIY projects with skin contact concerns
- Green building requirements
- Children's spaces or sensitive environments
Limitations
- Lower density limits low-frequency absorption
- May retain moisture
- Can be treated with fire retardants that off-gas
Polyester Fiber Panels
Properties
- Density: 2-4 lb/ft³
- Typical thickness: 1-2 inches
- NRC Rating: 0.6-0.85 at 1"
- Cost: $8-15 per square foot (finished panels)
Performance
Moderate absorption, often sold as finished decorative panels. Clean appearance without fabric wrapping needed. Pet-safe and non-irritating.
Best For
- Decorative office panels
- Residential applications where appearance matters
- Supplementary treatment in treated rooms
Limitations
- Thin panels have limited low-frequency absorption
- Premium price for finished appearance
- Less effective per inch than fiberglass
Material Selection Guide
By Application
| Application | Recommended Material |
|---|
| Bass trapping | Rigid fiberglass or rockwool, 6"+ |
| First reflections | Rigid fiberglass or rockwool, 4" |
| Ceiling clouds | Rigid fiberglass, 2-4" |
| Vocal booth | Any absorber, 4"+ coverage |
| Office panels | Polyester or compressed fiber |
| Budget DIY | Rockwool (best value) |
By Priority
Performance priority: Rigid fiberglass (OC 703/705) Budget priority: Rockwool (similar performance, lower cost) Handling ease: Rockwool or cotton (less irritating) Appearance: Polyester panels (finished look) Sustainability: Cotton, cellulose, or recycled polyester
Thickness Matters More Than Material
The most important factor for low-frequency absorption is thickness, not material choice. A 4" rockwool panel outperforms a 2" fiberglass panel despite fiberglass being "better" material.
For bass control: Use 4-6" minimum, preferably 8-12" in corners
For broadband: 4" provides good all-around performance
For HF only: 2" is sufficient (but rarely needed alone)
Air Gap Enhancement
Any absorber works better with an air gap behind it:
- 2" panel + 2" air gap ≈ 3" panel performance
- Particularly effective for extending low-frequency absorption
- Free performance upgrade
Mount panels 2-4" from wall surface using spacers or mounting hardware.
The Bottom Line
For most DIY acoustic projects, rockwool offers the best combination of performance, cost, and handling ease. For professional installations where maximum performance justifies cost, rigid fiberglass remains a leading choice.
Avoid thin foam as primary treatment. It addresses only part of the frequency spectrum and creates tonal imbalance.
Materials, Absorbers, Fiberglass, Rockwool, DIY
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