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8
C
ALIBRATION PROCEDURE
The HD 2020 can calibrate standard
1/2” microphones compliant with IEC 61094-1 and IEC61094-2.
To calibrate the microphone, insert it deep into the cavity. The O-ring will offer some resistance.
During calibration the HD2020 can be held in vertical position or placed on a flat surface.
While measuring, you should move neither the microphone nor the calibrator; make sure that the worktable
doesn’t transmit vibrations.
A small misalignment of the microphone and calibrator axes is allowed.
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Before beginning to calibrate, you should make sure that the ambient noise level
doesn’t affect
the calibration. After inserting the microphone into the cavity, with the sound level meter and the
calibrator off, switch on the sound level meter and detect the unweighted ambient sound pressure
level. If the measured level is below 78 dB, you can use both calibration sound levels (94 dB and
114 dB); if the level is between 78 dB and 98 dB you can use the 114 dB level only, while a sound
level above 98 dB means that calibration is not possible.
•
Press the ON/OFF key to switch on the instrument.
•
Use the arrow keys to select the sound level: 94 dB or 114 dB.
•
Make sure that the measurement value is not blinking on the display: this means that the micro-
phone is not inserted correctly.
•
Calibrate the sound level meter as per the procedure shown in the instrument manual.
•
Apply the correction to the pressure level depending on the microphone (see the following chap-
ter).
•
Once calibration is complete, switch off the sound level meter and the calibrator and remove the
microphone from the cavity.
