Author | Material | Sound Absorption Coefficient | Frequency (Hz) |
Dance and Shield [103] , Vorländer [104] | Smooth unpainted concrete | 0.01, 0.02, 0.05 | 125, 1000 and 4000 respectively |
Vorländer [104] | Rough concrete | 0.02, 0.03, 0.07 | - Ditto - |
Brick wall, stuccoed with rough finish | 0.03, 0.04, 0.07 | - Ditto - | |
Brickwork, with facing brick of dimensions 230 × 50 × 55 mm | 0.04, 0.35, 0.36 | - Ditto - | |
Thin plywood panelling | 0.42, 0.08, 0.06 | - Ditto - | |
Solid wooden door | 0.14, 0.08, 0.10 | - Ditto - | |
Tiuc et al. [105] | Sawdust and recycled Rubber granules | 0.65 0.979 | 300 - 3150 2000 |
Tiuc et al. [100] | Sawdust with 30% polyurethane binder | 0.1 - 0.89 | 450 - 1600 |
Tiuc et al. [102] | Composite material made of 50% Flexible Polyurethane Form and 50% fir sawdust | 0.09 - 0.89 | 100 - 800 |
Kang et al. [101] | Rice hull-sawdust composite boards | 0.2 0.4 0.40 - 0.55 | 500 1000 Above 1000 |