Chapter 4 — Free-field
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" Microphone Type 4190
Introduction
Falcon™ Range of Microphone Products
Microphone Handbook
Brüel & Kjær
4
−
4
The lower curve on the calibration chart is the individual microphone’s electrostatic
actuator response measured with Electrostatic Actuator UA0033. This response is
used to determine free-field responses at angles of incidence other than 0° and
responses in other types of sound field. The individual microphone’s electrostatic
actuator response is also available on the data disk.
The dotted part of the curve is the typical low-frequency response. Each micro-
phone’s individual lower limiting frequency is measured to ensure that it is within
the specified tolerances (see Fig.4.3).
4.1.3 Data Disk
The 3
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" data disk supplied with each microphone supplements the calibration
chart. It contains individual calibration data and correction curves (see Table 4.1)
with a frequency resolution of
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12
-octave as comma-separated ASCII text files un-
der the \DATA directory.
These text files can be viewed on Microsoft
®
Windows™ using the Brüel&Kjær
Microphone Viewer program (BK–MIC.EXE) supplied on the disk. They can also be
accessed by a suitable spreadsheet for further processing or printing.
Brüel&Kjær Microphone Viewer must be installed before use (see section 1.3.5).
a. Individual calibration data (measured).
b. Low-frequency response combined with actuator response and free-field corrections.
c. Typical response for Free-field
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" Microphone Type 4190.
d. Corrections for Free-field
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" Microphone Type 4190.
File Name Content Frequency Range
S#######.BKM
a
Sensitivity calibration 251.2Hz
A#######.BKM
a
Actuator response 200 Hz – 22 kHz
F#######.BKR
b
Free-field response 1 Hz – 22kHz
4190L.BKT
c
Low-frequency response 1 Hz – 190 Hz
4190F.BKC
d
Free-field corrections without protection grid 200 Hz – 22 kHz
4190FG.BKC
d
Free-field corrections with protection grid 200 Hz – 22kHz
4190R.BKC
d
Random-incidence corrections without protection grid 200 Hz – 22kHz
4190RG.BKC
d
Random-incidence corrections with protection grid 200 Hz – 22 kHz
4190P.BKC
d
Pressure-field corrections 200 Hz – 22 kHz
Table 4.1 Calibration data and corrections contained on the data disk. Note: ####### is the micro-
phone’s serial number
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