bb090813.book : 2236-ch4 Black 3
Chapter 4 – Measuring
Calibrating
BB 0908–13
4 – 3
Precision Integrating Sound Level Meter Type 2236
User Manual
Always remove the Random Incidence Corrector DZ9566 (if
fitted) from the microphone when calibrating or checking the
calibration.
Which Calibrators Can I Use?
The sound level meter can be calibrated with Sound Level
Calibrator Type 4231, Multifunction Acoustic Calibrator Type
4226 or a similar calibrator. All are referred to on the sound
level meter’s display as the calibrator.
Each calibrator is slightly different. The actual calibration
level is not necessarily equal to the nominal calibration level.
It is, therefore, important to set the calibration level to the
one given on the calibration chart for the calibrator used.
4.1.2
Calibrating the Sound Level Meter
Sound Level Calibrator Type 4231 provides a nominal pres-
sure field calibration signal of 94 or 114dB at 1kHz. The
nominal diffuse field calibration signal is also 94 or 114 dB
but the nominal free field calibration signal is 93.8 or
113.8 dB.
Multifunction Acoustic Calibrator Type 4226 provides a nom-
inal calibration signal of 94, 104 or 114dB at a range of
frequencies.
For day to day calibration, you only need to calibrate at one
level at one frequency. In order to comply with the standards,
calibrate the sound level meter with a reference signal of
94dB at 1kHz
*
.
* Calibration at frequencies other than 1 kHz requires correction for the frequency weighting
used (see Chapter 6). The sound level meter can correct up to
±
0.5 dB from the nominal
calibration level
