How can I use the calibration data for my microphone?
Hint: If the deviations are not big (<= 1 dB in the acoustic region), then we recommend to do no compensation at all.
Microphone calibration can be used in SysTune (PRO only) with the help of the Normalization plug-in.
In the plug-in you can click on "Add from file" and load any given calibration file.
Unfortunately you cannot load the normal calibration text lists you get from the manufacturers.
These lists show the measurements in dB for some (log-spaced) frequencies.
(these deviations have to be compensated, if the mic is used)
Hz, dB
20, -0.05
25, 0.04
32, -0.04
40, 0.02
50, -0.02
64, 0.000
80, 0.000
....
12700, 0.57
16000, 0.69
Interpolate this list to linear spaced frequencies:
Hz, dB
21.53, -0.05
43.07, 0.02
64.6, 0
86.1, 0
107.67, -0.02
129.2, 0
150.73, 0
....
22006.93, 0.75
22028.47, 0.755
22050, 0.76
These data can be used, to create an EASERA text file (etx).
Here is the etx file:
* SDA etx
* SampleRate [Hz] 44100
* DataType Frequency (Real + Imag)
* DataSubType Not Specified
* Unit Normalized
* X-Values yes
* Complex yes
* TimeSamples 2048
* Data 1025
Hz Normalized Normalized
0 0 0
21.53 0.994 0
43.07 1.002 0
64.60 1 0
86.13 1 0
107.67 0.998 0
129.20 1 0
150.73 1 0
.......
22006.93 1.090 0
22028.47 1.091 0
22050 1.091 0
* EOF
These real data are calculated from the dB values by real = 10^(dB/20)
There is a SPACE after the * and a TAB between the data.
If you want to have a better frequency resolution (10,8 Hz, for sample rate of 44100), you can interpolate the 2049 frequencies, for instance.