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145
Appendix B
Room Criterion Curves (RC)
Room Criterion curve's was introduced in 1981 by Blazier to primarily rate noise in
offices/room acoustics. This methodology calculates a numerical rating based on speech
interference and indicates any interference such as hissing, rumbling, or vibration.
SEL
Sound Exposure Level. The continuous SPL lasting one-second that would deliver the same
sound exposure as an accumulated exposure determined over a sampling interval (RTime).
SEL is typically determined with a 3 dB Exchange Rate, slow exponential time-weighting, and
without regard to an Integrating Threshold.
SPL
Sound pressure level. A ratio of one sound pressure to a reference pressure (See Reference
Pressure on page 141). Because of the enormous dynamic range of the human ear, the ratio
is calculated logarithmically by the formula below, where L
Burst duration, t (milliseconds)
Figure B-4: Impulse response to a tone burst
SEL
=
ER
log
SPL
⁄
RTI M E
∫
L ER
2
t d
2
0
is the reference pressure.
r
dB
L
=
20 log
---- -
L
r
dB
Models SE and DL
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