Frequency Response Calibrations Of Listed Microphones - BRUEL & KJAER 4226 User Manual

16 Multifunction Acoustic Calibrator Type 4226 – User Manual
3.4

Frequency Response Calibrations of Listed Microphones

Before a Calibration
1) Using the
Power
2) Check the battery condition. The
instrument.
3) Make sure that the microphone and the instrument being calibrated are isolated from
external noise and vibration.
When Ready to Calibrate
4) Set the
Microphone
Microphone
Setting
a
b
c
5) Set the
Sound Field
• Pressure for direct use when the coupler is loaded with a pressure response microphone
such as Type 4180
• Free-field for free-field response microphones and IEC sound level meters. Which of the
two Free-field positions to use depends on the type of microphone under calibration, see
the table above. Remember to set the sound field in the sound level meter to 'free-field'.
6) Set the
Function
7) Set the
Sound Level
• For calibrating frequency responses: Use 94 Lin., 104 Lin. or 114 Lin.. This will simulate
a constant free-field sound level in the coupler at all frequencies
• For calibrating the frequency response of the sound level meter with A-weighting
selected (or as a permanent feature): Use 94 Inv. A. This will ensure a constant A-
weighted sound level in the coupler at all frequencies
✐
When 94 Inv. A is selected, a sound level of 134 dB at 31.5 Hz will be produced in the
Please note:
coupler. If this is above the highest range of the instrument being calibrated, an external
attenuator will be necessary.
8) Switch
Power
switch, switch On Type 4226.
Batt. Low
switch to a, b or c, to match the type of microphone:
Type of Brüel & Kjær ½" Microphone
Traditional
4129, 4130, 4176
4155, 4165
4133, 4134, 4147, 4149
switch according to the required simulated frequency response:
switch to Calibration.
switch to give the required level in the coupler:
On (if not already).
LED should remain off. You can switch Off the
Falcon
4187, 4188
4189, 4190
4191, 4192, 4193