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Appendix B
145
Models SE and DL
Figure B-4: Impulse response to a tone burst
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
r
is the reference pressure.
SPL 20 log
L
L
r
-----
dB=
SEL ER log
2
2
L ER⁄
td
0
RTIME
∫
dB=
Relative response (dB)
Burst duration, t (milliseconds)