Casella CEL CEL-62X - Manual (Page 37)

Sound Calibrators – Level Corrections
Sound level calibrators apply sound pressure to a microphone in a closed cavity.
The response of a microphone in a free field at 1kHz will be slightly different to that of
a pressure field. Also some calibrators are affected by the volume of the microphone
changing the volume of the calibrator cavity.
The wind screen has an affect on the free field response at 1kHz and this can be
compensated for during calibration.
Calibration corrections for the CEL-251 and CEL-252 Microphones.
Calibrator Calibration Level
Correction no Wind
Screen
Calibration Level
Correction with
Wind Screen
IEC 60942
Casella CEL-110/1 -0.1dB 0.0dB Type 1
Casella CEL-110/2 -0.1dB 0.0dB Type 2
Bruel & Kjear 4231 -0.1dB 0.0dB Type 1 approved
Cirrus CR:515 -0.1dB 0.0dB Type 1 approved
Examples
The CEL-62X can be calibrated at a nominal level of 94dB or 114dB dependent on
the type of calibrator used.
If a CEL-110/1 is used and the certified output of the calibrator is 113.98dB, and it is
intended to use the sound level meter without the wind screen, then the calibration
level will need to be set to 113.88, rounded to 113.9dB.
Calibrator level
113.98
Correction -0.1
Calibration level = 113.88 rounded to 113.9dB
If a Cirrus CR:515 is used and the certified output of the calibrator is 94.04dB, and it
is intended to use the sound level meter with the wind screen fitted, then the
calibration level will need to be set to 94.04, rounded to 94.0dB
Calibrator level
94.04
Correction 0.0
Calibration level = 94.04 rounded to 94.0dB
See Section G. in the manual to set the calibration level.
See Section K. in the manual to calibrate the sound level meter.
Casella CEL Limited 37