Page 239 - The Master Handbook Of Acoustics
P. 239
214 CHAPTER NINE
1.2
A
1.0
Insulation toward sound
0.8
0.6 Kraft paper toward sound
R-19
0.4
0.2
Absorption coefficient 1.2 125 250 500 Frequency - Hz 2 kHz 4 kHz
0
1 kHz
1.0
Insulation toward sound
0.8
0.6 Kraft p aper toward sound
R-11
0.4
0.2
B 0
125 250 500 1 kHz 2 kHz 4 kHz
Frequency - Hz
FIGURE 9-29
When ordinary building insulation is used as a wall treatment (perhaps with fabric fac-
ing) the position of the kraft paper backing becomes important. (A) R-19 Fiberglass
building insulation, (B) R-11 Fiberglass building insulation, Mounting A.
room treatment. With insulation exposed there is essentially perfect
absorption above 250 Hz (R-19) or 500 Hz (R-11).
Building insulation has not caught on as an inexpensive absorbing
material. One reason is that some sort of cosmetic and protective cover
is required, but this is often true of denser materials as well. Fabric,