Introduction to Acoustics

Table 11.4 Transmission loss and STC values for common partitions
Building Acoustics 11.1 Room Acoustics 397
Partition 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz STC
1/2 inch drywall on both 17 31 33 40 38 36 33
sides of wooden studs
1/2 inch drywall on wooden 15 30 34 44 46 41 37
studs with 2 inches of insulation
Double layer of 1/2inch 25 34 41 51 48 50 41
drywall on wooden studs
1/2inchdrywallon 23 28 39 46 54 44 39
staggered wooden studs
1/2 inch drywall on staggered 29 38 45 52 58 50 48
wooden studs with 2 inches of insulation
1/2 inch drywall on metal studs 22 27 43 47 37 46 39
1/2 inch drywall on metal studs 26 41 52 54 45 51 45
with 2 inches of insulation
8 inch thick concrete 36 44 50 54 58 56 53
masonry units
Open-plane office partition 10 12 12 12 12 11 12
4 inch thick brick wall 32 34 40 47 55 61 45
1/2inchdrywallinside/1inch 21 33 41 46 47 51 42
stucco outside on wooden studs
Single-paned 1/8 inch thick glass 18 21 26 31 33 22 26
1/2 inch thick laminated glass 31 34 38 40 37 46 40
Double-paned 1/8 inch thick 13 25 35 44 49 43 37
glasswith2inchairgap
Hollow wooden door, 1 3/4inchthick 14 19 23 18 17 21 19
Solid wooden door, 1 3/4inchthick 29 31 31 31 39 43 34
Hollow metal door, 1 3/4inchthick 24 23 29 31 24 40 28
Filled metal door, 1 3/4inchthick 26 34 40 48 44 52 43
Wood joist floor/ceiling with 1/2inch 23 32 36 45 49 56 37
plywood subfloor and 1/2inchdrywall
8 inch thick concrete slab floor 32 38 47 52 57 63 50
Wood plank shingled roof 29 33 37 44 55 63 43
Wood plank shingled roof with 1/2inch 35 42 49 62 67 79 53
drywall ceiling, 4 inches of insulation
Corrugated steel roof with 1 inch 17 22 26 30 35 41 30
of sprayed cellulose
E 989. The IIC stresses the low-frequency range, as
isshowninFig.11.16, but note that IIC does not address
very low (below 100 Hz) frequencies, which may
be associated with resonances of a building’s structural
components.
One other single-number rating worth noting here
is the outdoor–indoor transmission class (OITC), established
in ASTM E 1332. The OITC is a single-number
rating for the effectiveness of a building façade in reducing
noise to interior spaces. The calculation of OITC
is based on an A-weighted source spectrum of typical
transportation (aircraft, rail, and traffic) sources in the
80–4000 Hz range and the façade’s transmission loss
spectrum in the same frequency range.
Non-Homogeneous Partitions
Up to this point we have been discussing homogeneous
partitions. Actual designs, however, include walls composed
of different materials, such as those with windows
and doors. Each of these wall components has different
associated TL characteristics. Wall components having
lower TL characteristics than the rest of the wall can
significantly degrade a wall’s sound reduction effectiveness.
This can be calculated using the composite
Part C 11.1