Handbook of air conditioning and refrigeration / Shan K

TABLE 19.14 Transmission Loss of Some Building Structures
Transmission Loss for Selected Building Structures
The transmission losses for selected building structures—including walls, partitions, window glass,
ceiling and plenum, and acoustic equipment housing—are listed in Table 19.14. These are mainly
abridged from ASHRAE Handbook 1991, HVAC Applications. In Table 19.14, the combined
plenum/ceiling cavity effect indicates the combined effect of the plenum sound absorption and the
transmission through the ceiling material. These values are based on data from several manufacturers’
laboratory and mock-up spaces.
19.7 RELATIONSHIP BETWEEN ROOM SOUND POWER LEVEL
AND ROOM SOUND PRESSURE LEVEL
The sound pressure level at a given location in a room corresponding with a particular point source
or an array of multiple sound sources is a function of the sound power level and transmission characteristic
of the sound source, the room’s acoustical properties, and the distance between the sound
source and the receiver.
Single or Multiple Sound Sources
Octave band center frequency, Hz
SOUND CONTROL 19.23
Building structures 63 125 250 500 1000 2000 4000
4-in. dense concrete or solid concrete block, 48 lb/ft 2 32 34 35 37 42 49 55
4-in. hollow-core dense aggregate concrete block, 28 lb/ft 2 29 32 33 34 37 42 49
8-in. hollow-core dense aggregate concrete block 31 33 35 36 41 48 54
Standard drywall partition, -in. gypsum board
on both sides of 2-in. � 4-in. wood studs 12 17 34 35 42 38 44
Standard drywall partition, two layers of -in.
gypsum board on each side of 3 -in. metal studs 25 36 43 50 50 44 55
-in. plate glass 11 16 23 27 32 28 32
Double glazing, two -in. panes, -in. airspace 12 16 23 27 32 30 35
-in. Gypsum board ceiling
Roof construction, 6 in. thick, 20 gauge (0.0396-in).
9 15 20 25 31 33 27
steel deck with 4-in. lightweight concrete topping, -in.
gypsum board ceiling on resilient hangers
*Plenum/ceiling
*Plenum/ceiling cavity effect: lay-in mineral fiber tile
25 41 47 56 65 68 69
in., 35 lb/ft 3 5 9 10 12 14 15
*Plenum/ceiling cavity effect: finished sheetrock, in.
Acoustic equipment housing, 20-gauge steel outer shell,
2-in.-thick acoustic insulation, 22-gauge (0.0336-in.)
10 15 21 25 27 26 27
perforated inner shell 15 18 21 39 38 49 55
Solid-core wood door, normally closed † 5�8 5�8 5�8 1�2 1 1
�2 �2
5�8 5�8 5�8 5�8 23 27 29 27 26 29
*ASHRAE Transactions, 1989, Part I.
† Handbook of HVAC Design, 1990.
Source: ASHRAE Handbook 1991, HVAC Applications.
Based on field measurements, Schultz (1985) recommended the following empirical formula to
estimate the room sound pressure level L pr, in dB re 20 �Pa, from the room sound power level of