Sound Absorption Coefficients
On this page you will find a compilation of “alpha” sound absorption coefficients of current materials and constructive solutions used in construction.
LogAcústica makes available, free of charge, for everyone who wants to develop acoustic projects, acoustic conditioning of spaces or even acoustic insulation, the main data it uses in the calculation models for the elaboration of Building Acoustics Projects and Studies of Acoustic Rehabilitation of Buildings.
The choice of materials for your acoustic project is vital to obtain the acoustic performance you want. If you are not a specialist in acoustics, note that there are materials with low sound absorption such as concrete, masonry, etc. There are others that absorb a lot of noise such as cork, acoustic foams, acoustic panels, etc. The characterization of the material’s ability to absorb noise significantly is carried out through laboratory tests where the “alphas” per frequency band are determined. These are the values that are used to calculate and predict the acoustic performance that your space will have and that we provide you here.
If you want to improve the acoustics of your space, be it a studio, a classroom, a multipurpose room, a church, a factory, you should bear in mind that it is in the balance of the choice of materials that a space without acoustic defects such as echoes, excess reverberation or even low sound insulation that make the space acoustically uncomfortable.
We are at your disposal to study the best sound absorption solution to apply to your problem or to supply the most suitable material for the work you are developing. Please contact us for more information.
The table of “alpha” sound absorption coefficients will be updated regularly. If you have other values you wish to disclose, please contact us.
| WALLS & CEILINGS | 125 | 250 | 500 | 1000 | 2000 | 4000 | NRC | Source |
|---|---|---|---|---|---|---|---|---|
| Concrete, plastered brick | 0.01 | 0.01 | 0.01 | 0.02 | 0.02 | 0.03 | 0.00 | EN 12354-6 |
| Wood, rigid backing | 0.04 | 0.04 | 0.03 | 0.03 | 0.03 | 0.02 | 0.05 | Arau |
| Plasterboard on frame (13 mm, 10 cm empty cavity) | 0.08 | 0.11 | 0.05 | 0.03 | 0.02 | 0.03 | 0.05 | Cox |
| Plasterboard on frame (2x13mm, 5 cm mineral wool cavity) | 0.15 | 0.10 | 0.06 | 0.04 | 0.04 | 0.05 | 0.05 | Cox |
| Plasterboard on frame (13 mm, 10 cm mineral wool cavity) | 0.30 | 0.12 | 0.08 | 0.06 | 0.06 | 0.05 | 0.10 | Cox |
| Wood (9,5-12,7 mm) with air cavity (5-10 cm) | 0.30 | 0.25 | 0.20 | 0.17 | 0.15 | 0.10 | 0.20 | Cox |
| 125 | 250 | 500 | 1000 | 2000 | 4000 | NRC | ||
| Solid floor (concrete, marble, ceramic) | 0.01 | 0.01 | 0.01 | 0.01 | 0.02 | 0.02 | 0.00 | Patrício |
| Linoleum or vinyl on concrete | 0.02 | 0.02 | 0.03 | 0.04 | 0.04 | 0.05 | 0.05 | Cox |
| Wood on solid floor | 0.04 | 0.04 | 0.03 | 0.03 | 0.03 | 0.02 | 0.05 | Cox |
| Wooden floor, parquet on battens | 0.12 | 0.10 | 0.06 | 0.05 | 0.05 | 0.06 | 0.05 | EN 12354-6 |
| Wood platform, large airspace below | 0.40 | 0.30 | 0.20 | 0.17 | 0.15 | 0.10 | 0.20 | Cox |
| Thin carpet on concrete | 0.02 | 0.04 | 0.08 | 0.20 | 0.35 | 0.40 | 0.15 | Cox |
| Heavy carpet on concrete | 0.02 | 0.06 | 0.14 | 0.37 | 0.60 | 0.65 | 0.30 | Cox |
| 125 | 250 | 500 | 1000 | 2000 | 4000 | NRC | ||
| Water surface in swimming pool | 0.01 | 0.01 | 0.01 | 0.01 | 0.02 | 0.02 | 0.00 | Cox |
| Windows, glass facade | 0.12 | 0.08 | 0.05 | 0.04 | 0.03 | 0.02 | 0.05 | EN 12354-6 |
| Door (wood) | 0.14 | 0.10 | 0.08 | 0.08 | 0.08 | 0.08 | 0.10 | EN 12354-6 |
| Air grid (50% open area) | 0.50 | 0.50 | 0.50 | 0.50 | 0.50 | 0.50 | 0.50 | EN 12354-6 |
| Large openings (small dimension > 1 m) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | EN 12354-6 |
| 1D N=7 QRD Diffuser | 0.11 | 0.10 | 0.07 | 0.08 | 0.06 | 0.06 | 0.10 | Cox |
| 2D N=7 QRD Diffuser | 0.14 | 0.12 | 0.14 | 0.20 | 0.09 | 0.12 | 0.15 | Cox |
| 125 | 250 | 500 | 1000 | 2000 | 4000 | NRC | ||
| 2 cm expanded cork agglomerate, rigid backing | 0.01 | 0.04 | 0.07 | 0.40 | 0.70 | 0.80 | 0.30 | LNEC |
| 4 cm expanded cork agglomerate, rigid backing | 0.09 | 0.09 | 0.35 | 0.60 | 0.38 | 0.49 | 0.35 | LNEC |
| 2,5 cm polyurethane foam | 0.16 | 0.25 | 0.45 | 0.84 | 0.97 | 0.87 | 0.65 | Cox |
| 5 cm mineral wool (40 kg/m3), rigid backing | 0.26 | 0.63 | 0.96 | 1.00 | 1.00 | 0.92 | 0.90 | LNEC |
| 5 cm fibreglass (50 kg/m3), rigid backing | 0.18 | 0.59 | 1.00 | 1.00 | 1.00 | 0,99 | 0.90 | LNEC |