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Appendix B
137
Models SE and DL
Glossary of Terms
C-A
The C-A measurement is an SPL average that enhances the low- frequency components of
the sound signal.
Figure B-1: C-A weighting response curve
Center frequency
The center frequency of each octave and third octave filter band.
CNEL
Community Noise Exposure Level. The accumulated exposure to sound measured in a 24-
hour sampling interval and artificially boosted during certain hours. For CNEL, samples taken
between 7 p.m. and 10 p.m. are boosted by 5 dB; samples taken between 10 p.m. and 7 a.m.
are boosted by 10 dB. The values reported by SoundPro SE/DL ignore the threshold and use
a 3 dB Exchange Rate, regardless how those parameters are set.
Criterion Level
Criterion Level. The average SPL that would result in 100% dose over the Criterion Time
(usually 8 hours).
APPENDIX
B