Civil Engineering Reference
In-Depth Information
1.0
0.9
25 Pa
.
s/m
0.8
0.7
10 Pa
.
s/m
0.6
0.5
0.4
5 Pa
.
s/m
0.3
0.2
0.1
0.0
200
400
600
800
2000
4000
100
1000
Frequency (Hz)
Figure 5.12
Absorption factor at normal incidence. Hole-perforated plate backed
by a cavity of depth 100 mm.
For further specifications, see text.
1.2
1.1
3
1
0.9
2
0.8
0.7
0.6
1
0.5
0.4
7.5
0.3
3
4
14
0.2
Fabric
0.1
0
125
250
500
1000
2000
4000
Frequency (Hz)
Figure 5.13
Absorption factor measured in a reverberation chamber. 14 mm perforated panel, perforation rate
12%, with a layer of fabric backed by a cavity of depth 50 mm. Curve no. 1 - cylindrical holes, empty cavity.
Curve no. 2 - cylindrical holes, cavity filled with mineral wool. Curve no. 3 - conical holes, cavity filled with
mineral wool.
