Absorption Coefficient Chart

ABSORPTION COEFFICIENT CHARTI got this chart off the web and it gives you an idea of how the different materials absorb sound at different frequencies.Remember that full absorption is 1 whilst full reflection is 0Absorption coefficients of common building materials and finishesFloor materials125 Hz250 Hz500 Hz1 kHz2 kHz4 kHz

carpet0.010.020.060.150.250.45

Concrete (unpainted, rough finish)0.010.020.040.060.080.1

Concrete (sealed or painted)0.010.010.020.020.020.02

Marble or glazed tile0.010.010.010.010.020.02

Vinyl tile or linoleum on concrete0.020.030.030.030.030.02

Wood parquet on concrete0.040.040.070.060.060.07

Wood flooring on joists0.150.110.10.070.060.07

Seating materials125 Hz250 Hz500 Hz1 kHz2 kHz4 kHz

Benches (wooden, empty)0.10.090.080.080.080.08

Benches (wooden, 2/3 occupied)0.370.40.470.530.560.53

Benches (wooden, fully occupied)0.50.560.660.760.80.76

Benches (cushioned seats and backs, empty)0.320.40.420.440.430.48

Benches (cushioned seats and backs, 2/3 occupied)0.440.560.650.720.720.67

Benches (cushioned seats and backs, fully occupied)0.50.640.760.860.860.76

Theater seats (wood, empty)0.030.040.050.070.080.08

Theater seats (wood, 2/3 occupied)0.340.210.280.530.560.53

Theater seats (wood, fully occupied)0.50.30.40.760.80.76

Seats (fabric-upholsterd, empty)0.490.660.80.880.820.7

Seats (fabric-upholsterd, fully occupied)0.60.740.880.960.930.85

Reflective wall materials125 Hz250 Hz500 Hz1 kHz2 kHz4 kHz

Brick (natural)0.030.030.030.040.050.07

Brick (painted)0.010.010.020.020.020.03

Concrete block (coarse)0.360.440.310.290.390.25

Concrete block (painted)0.10.050.060.070.090.08

Concrete (poured, rough finish, unpainted)0.010.020.040.060.080.1

Doors (solid wood panels)0.10.070.050.040.040.04

Glass (1/4" plate, large pane)0.180.060.040.030.020.02

Glass (small pane)0.040.040.030.030.020.02

Plasterboard (12mm (1/2") paneling on studs)0.290.10.060.050.040.04

Plaster (gypsum or lime, on masonry)0.010.020.020.030.040.05

Plaster (gypsum or lime, on wood lath)0.140.10.060.050.040.04

Plywood (3mm(1/8") paneling over 31.7mm(1-1/4") airspace)0.150.250.120.080.080.08

Plywood (3mm(1/8") paneling over 57.1mm( 2-1/4") airspace)0.280.20.10.10.080.08

Plywood (5mm(3/16") paneling over 50mm(2") airspace)0.380.240.170.10.080.05

Plywood (5mm(3/16") panel, 25mm(1") fiberglass in 50mm(2") airspace)0.420.360.190.10.080.05

Plywood (6mm(1/4") paneling, airspace, light bracing)0.30.250.150.10.10.1



Absorptive wall materials125 Hz250 Hz500 Hz1 kHz2 kHz4 kHz

Drapery (10 oz/yd2, 340 g/m2, flat against wall)0.040.050.110.180.30.35



Drapery (14 oz/yd2, 476 g/m2, pleated 50%)0.070.310.490.750.70.6

Drapery (18 oz/yd2, 612 g/m2, pleated 50%)0.140.350.530.750.70.6

Fiberglass board (25mm(1") thick)0.060.20.650.90.950.98




Open brick pattern over 75mm(3") fiberglass0.40.650.850.750.650.6

Pageboard over 25mm(1") fiberglass board0.080.320.990.760.340.12



Performated metal (13% open, over 50mm(2") fiberglass)0.250.640.990.970.880.92

Ceiling material125 Hz250 Hz500 Hz1 kHz2 kHz4 kHz

Plasterboard (12mm(1/2") in suspended ceiling grid)0.150.110.040.040.070.08

Underlay in perforated metal panels (25mm(1") batts)0.510.780.570.770.90.79

Metal deck (perforated channels,25mm(1") batts)0.190.690.990.880.520.27

Metal deck (perforated channels, 75mm(3") batts)0.730.990.990.890.520.31

Plaster (gypsum or lime, on masonary)0.010.020.020.030.040.05

Plaster (gypsum or lime, rough finish or timber lath)0.140.10.060.050.040.04

Sprayed cellulose fiber (16mm(5/8") on solid backing)0.050.160.440.790.90.91

Sprayed cellulose fiber (25mm(1") on solid backing)0.080.290.750.980.930.76

Sprayed cellulose fiber (25mm(1") on timber lath)0.470.91.11.031.051.03

Sprayed cellulose fiber (32mm(1-1/4") on solid backing)0.10.30.730.920.980.98

Sprayed cellulose fiber (75mm(3") on solid backing)0.70.9510.850.850.9

Wood tongue-and-groove roof decking0.240.190.140.080.130.1

Miscellaneous surface material125 Hz250 Hz500 Hz1 kHz2 kHz4 kHz

People-adults (per 1/10 person)0.250.350.420.460.50.5

People-high school students (per 1/10 person)0.220.30.380.420.450.45

People-elementary students (per 1/10 person)0.180.230.280.320.350.35

Ventilating grilles0.30.40.50.50.50.4

Water or ice surface0.0080.0080.0130.0150.020.025

RT60 relates to intelligibility. Diffractors reduce pronounced reflection by breaking up the sound wave before reflecting it back. This does not reduce reverberant energy, but does reduce echo spikes that may otherwise exceed -60db of direct, thus lowering RT60 and improving intelligibilty,but not necessarily improving the listening environment for music.

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Absorption Coefficient Chart