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inary and have the extension .SO8. An example on a directivity pattern is the pattern stored in
OMNI.SO8.
Entering a directivity plot using the Directivity polar plot editor
The easiest way to enter a
new directivity plot is to use
the built-in polar plot editor
which allows building a
directivity plot from a
vertical and a horizontal
polar plot.
Enter the dB values (sound
pressure level) for the
horizontal and vertical plots
at the selected frequency
band in the corresponding
tables. The angular
resolution is 10º degrees. If
data are not entered for all
angles e.g. if the data are
not available, ODEON will
do interpolation between
the angles entered. For
angles between the polar plots, ODEON will perform elliptical interpolation.
Equalization
If the source to be used in ODEON has a fixed frequency dependent sound power level the
equalization option in the Polar plot editor is used for entering the dB values.
Calibration
Three different options are available in the Polar plot editor:
If No calibration is selected, ODEON will use the SPL dB values as entered in the polar plot
table, adding the equalization values entered. This option is typically used if the source
is a loudspeaker.
If Calibrated source is selected ODEON will add the equalization if entered, then shift the
resulting SPL's of the source in order to obtain a reference sound power level of 0 dB re
10 -12 Watt at the selected Calibration frequency band (typically 1kHz). This calibration type is
typically used when a generic source with an adjustable level is needed for calculations,
such as the OMNI or SEMI directivity pattern,
If Sensitivity calibration is selected the SPL's of the source will be shifted in order to obtain the
SPL in dB on front axis of the source at the distance specified as Ref. distance metres
at the selected Calibration frequency band. This calibration type is typically used if the free
field sound pressure level measurements are available for a natural source.
Maximum dynamic range
The ‘minimum level’ will be 'Max level’ minus ‘Maximum dynamic range'. If the range is large
the display may be difficult to interpret /view in the directivity viewer. The source will usually
have its max levels on its axis.
Text format
Normally the text format should not be necessary to use, as most common sources are
defined already in ODEON or available on www.clfgroup.org.
The data entered in the text format should be in relative calibration across frequencies, but
need not be in any absolute calibration. The absolute calibration is an option, from within the
program as described under the chapter below: “Creating a new directivity pattern using a
text file as input”.
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