Sound Absorption Coefficients

125Hz

250Hz

500Hz

1000Hz

2000Hz

4000Hz

Brick, unglazed

.03

.04

.05

.07

Brick, unglazed, painted

.01

.02

.03

Carpet, heavy, on concrete

.02

.06

.14

.37

.60

.65

Same, on 40oz hairfelt or foam rubber

.08

.24

.57

.69

.71

.73

Same, with impermeable latex backing on 40oz hairfelt or foam rubber

.08

.27

.39

.34

.48

.63

Concrete Block, light, porous

.36

.44

.31

.29

.39

.25

Concrete Block, dense, painted

.10

.05

.06

.07

.09

.08

Fabrics:

Light Velour, 10oz per sq yd, hung straight, in contact with wall

.03

.04

.11

.17

.24

.35

Medium Velour, 14oz per sq yd, draped to half area

.07

.31

.49

.75

.70

.60

Heavy Velour, 18-oz per sq yd, draped to half area

.14

.35

.55

.72

.70

.65

Floor:

Concrete or Terrazzo

.01

.015

.02

Linoleum, asphalt, rubber, or cork tile on concrete

.02

.03

.02

wood

.15

.11

.10

.07

.06

.07

Wood parquet in asphalt on concrete

.04

.07

.06

.07

Glass:

Large panes of heavy plate glass

.18

.06

.04

.03

.02

Ordinary window glass

.35

.25

.18

.12

.07

.04

Gypsum Board, 1/2-inch, nailed to 2x4's 16 inches o.c.

.29

.10

.05

.04

.07

.09

Marble or glazed tile

.01

.02

Plaster, gypsum, or lime, smooth finish on tile or brick

.013

.015

.02

.03

.04

.05

Plaster, gypsum, or lime, rough finish on lath

.14

.10

.06

.05

.04

.03

Same, with smooth finish

.14

.10

.06

.04

.03

Plywood Paneling, 3/8-inch thick

.28

.22

.17

.09

.10

.11

Water surface, as in a swimming pool

.008

.013

0.15

.020

0.25

Air, Sabins per 1000 cubic feet

.09

.20

.49

1.20

2.90

7.40

Open doors and windows

1.00

Values below are given in Sabins per square foot of seating area or per unit

Absorption of Seats and Audience

125Hz

250Hz

500Hz

1000Hz

2000Hz

4000Hz

Chairs, metal or wood seats, each, unoccupied

.15

.19

.22

.39

.38

.30

People in a room, per person, (do not use for auditorium calculations

2

3

4

5

4

Audience, seated in upholstered seats, per square foot of floor area, for auditorium calculations

.60

.74

.88

.96

.93

.85