Multifunction Acoustic Calibrator Type 4226 – User Manual
10
• Microphone:
Use this switch to set the microphone type under calibration. When correctly set, a free-field
frequency response check may be made. Corrections for each microphone group as well as
the 0 ° incidence free-field responses are automatically applied to the signal in the coupler.
The microphone type numbers for each setting are as follows:
None of these corrections are applied for pressure response checks. For frequency response
calibrations of unlisted microphones, see section 3.5
• Sound Field:
Use this switch to select between frequency response checks. All the corrections are based on
the discrete frequencies of the built-in tone generator.
– Pressure: Used for obtaining pressure responses regardless of the Microphone selected.
The selected Sound Level produced in the coupler when it is loaded by a Type 4180
microphone is the same at all selected discrete frequencies. Other microphone types will
load the coupler differently with resulting deviations at high frequencies.
This setting is mainly for making comparative measurements and should be the only
setting used in connection with microphones not listed under Microphone setting “a”,
“b” or “c”. For frequency response calibrations of unlisted microphones, see section 3.5
✐Please note: The coupler is “loaded” by the microphone inserted into it.
– Free Field (Falcon and Traditional): Both settings are used for free-field responses, but
for different ranges of Brüel & Kjær microphones, based on Microphone setting “a”, “b”,
or “c”. The selected Sound Level produced in the coupler is corrected at each selected
discrete frequency to simulate the 0° degree frequency response of the specified
microphone group measuring sound in a free field.
✐Please note: Valid only for the microphones listed above and when the Microphone setting agrees with
the actual microphone under test.
– Sound Level = 94 Inv. A: The Sound Field setting is as above, except that the sound level
in the coupler will also be inversely A-weighted at each selected discrete frequency. This
allows instruments with fixed A-weighting networks to be checked for frequency
response.
Use this setting also for checking A-weighting networks.
Microphone
Setting
Type of Brüel & Kjær ½″ Microphone
Traditional Falcon
a 4129, 4130, 4176 4187, 4188
b 4155, 4165 4189, 4190
c 4133, 4134, 4147, 4149 4191, 4192, 4193
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