TM 5-805-4/AFJMAN 32-1090
Region A: High probability that noise-induced vibration levels in lightweight
wall and ceiling constructions will be clearly feelable; anticipate audible rattles
in light fixtures, doors, windows, etc.
Region B: Noise-induced vibration levels in lightweight wall and ceiling con-
structions may be moderately feelable; slight possibility of rattles in light fix-
tures, doors, windows, etc.
Region C: Below threshold of hearing for continuous noise.
Reprinted with permission from
The 1987 ASHRAE Handbook,
HVAC Systems and Applications
Figure 2-2. Room Criterion (RC) Curves
d. Limitations. The indoor noise criteria consid-
The quality of telephone usage is related to SIL
ered above assume that the noise is almost contin-
approximately as follows:
uous and of a fairly steady nature (not enough
SIL Range (dB) for Telephone Usage
modulating or fluctuating up and down in level or
Satisfactory
30-45
frequency to attract attention), and there are no
Slightly difficult
45-60
Difficult
raucous, unpleasant sounds or strongly tonal
60-75
sounds. If any of these assumptions are not met,
Unsatisfactory
Above 75
2-3
Previous Page
