3M DL, SE Glossary of Terms

Appendix B
137
Models SE and DL
Glossary of Terms
C-A
The C-A measurement is an SPL average that enhanc es 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 octa ve filter band.
CNEL
Community Noise Exposure Level. The accumulated exposure to sound measured in a 24-
hour sampling interval and artificially boosted dur ing certain hours. For CNEL, samples taken
between 7 p.m. and 10 p.m. are boosted by 5 dB; sam ples taken between 10 p.m. and 7 a.m.
are boosted by 10 dB. The values reported by SoundP ro SE/DL ignore the threshold and use
a 3 dB Exchange Rate, regardless how those param eters are set.
Criterion Level
Criterion Level. The average SPL that would result in 100% dose over the Criterion Time
(usually 8 hours).
APPENDIX
B