Page 256 - The Master Handbook Of Acoustics

231
ABSORPTION OF SOUND

1
3
neutral modules are desired, they can be covered with 8″ and 4″ ply-
wood, which would give relatively low absorption with a peak around
70 Hz. Using these three or four modules as acoustical building blocks,
the desired effect can be designed into a studio by specifying the num-
ber and distribution of each of the basic types.
Figure 9-41 shows an adaptation from BBC practice where the wall
is used as the “bottom” of the module box. In this case the module
size is 2 4 ft. The modules are fastened to the 2 2″ mounting
strips, that in turn are fastened to the wall. A studio wall 10 ft high

4'-0" 8"

Hi perf Grill cloth
2'-0"

Lo perf 2

(A) Bass absorber (B) Wideband absorber

Air space
6–7" depth Air space
6–7" depth
1" Fiberglass
5–8 lb./cu. ft.
density 1" Fiberglass
25 Percent perf 5-8 lb./cu. ft.
0.5 Percent perf or more or density
(26 3 /16" holes no perf cover
per sq. ft.)
1 1
1"

2 2

FIGURE 9-41
Plan for a practical module absorber utilizing the wall as the bottom of the module. (Left) Bass absorber.
(Right) Wideband absorber.