TM 5-805-4/AFJMAN 32-1090
Table 4-6. Transmission Loss (in dB) of Stud-Type Partitions.
Octave
Improvements
Type
Type
Type
Band
(Hz)
1
2
3
A
B
31
4
9
6
2
2
63
10
16
12
2
2
125
17
24
20
3
2
250
26
34
30
3
3
500
34
42
39
4
4
1000
40
48
46
4
4
2000
46
46
52
3
5
4000
44
48
50
3
6
8000
48
52
54
3
5
STC
37
44
41
3
3
Notes :
Type 1 One layer 1/2=in. thick gypsum wallboard on each side of 2x4-in.
wood studs on 16-in. centers. Fill and tape joints and edges; finish
as desired. For equal width metal studs, add 2 dB in all bands and to
STC.
Type 2 Two layers 5/8-h. thick gypsum wallboard on each side of 2x4-in.
wood studs on 16-in. centers. Fill and tape Joints and edges; finish as
desired. For equal width metal studs, add 3 dB in all bands and to STC.
Type 3 One layer 5/8-in. thick gypsum wallboard on outer edges of staggered
studs, alternate studs supporting separate walls.
2x4 in. wood studs
on 16-in. centers for each wall. Fill and tape joints and edges ; finish
as desired. For equal width metal studs, add 1 dB in all bands and to STC.
(Notes continued next sheet)
improves if the space is larger than this. The
"high TL" variety. This means that the material
estimate TL of a Type 2 floor-ceiling is given in
is of high density and usually has a foil backing to
table 4-13 for a few typical dimensions of concrete
decrease the porosity of the back surface of the
floor slab thickness and air space. Interpolate or
material. Most acoustical ceiling materials manu-
extrapolate for dimensions not given in the table.
facturers produce "high TL" products within their
Increased mass is most beneficial at low frequency
lines. An alternate version of the Type 3 combina-
and increased air space is helpful across all fre-
tion includes a suspended ceiling system of light-
quency bands.
weight metal panel sandwich construction, consist-
(3) Type 3 floor-ceiling. This floor-ceiling com-
ing of a perforated panel on the lower surface and
bination is very similar to the Type 2 combination
a solid panel on the upper surface, with acoustic
except that the acoustic tile material is of the
absorption material between. The minimum NRC
4-11
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