Directivity files

You can easily download loudspeaker directivity files supported by the Common Loudspeaker Format: .CF1 and .CF2 from the CLFgroup homepage. The viewer provides a detailed view of the CLF file and once it is downloaded and installed in your PC ODEON automatically recognises it. A button for lunching the viewer is displayed in the point source editor together with the default Show Directivity Balloon tool in ODEON. 

 

Your new directivity pattern files e.g. 'Loudspeaker.CF2' should be saved at the default path for directivity pattern files (e.g. C:\Odeon12Combined\Dirfiles\). The Windows Explorer can be opened at this location from within ODEON program using the menu 'Options|Explorer directivity files folder (to install...)'.

Understanding the CLF format

The CLF format provides sound pressue levels on a spherical grid around the source in polar coordinates (directivity balloon), that is, as a function of the azimuth θ and elevation Φ. The discretization of the grid comes every 10 degrees for the .CF1 format and every 5 degrees for the .CF2 format. In the way the sphere around the source is descretized more measurement points are concetrated at the poles of the balloon than the circumference. Therefore, the are covered by each measurement point in the directivity ballon is smaller at the poles. This is taken into account when ODEON calculates the average power level of the source (see next section).

How does ODEON interpret CLF files?

Several procedures are applied on a CLF file before ODEON can use the data for simulations:

 

1) The average Sound Pressure Level, SPL, is calculated by an indegration over the directivity balloon. Directivity data at the poles are given less weight in the integration than data at the circumference.

2) The power level is calculated from the SPL and it is shown as the Sound Power File in the Point Source Editor.

3) Any extra overall Gain or further Equalization may be applied to the Sound Power File so that a final Sound Power is derived (Red values in the Point Source Editor).

4) The SPL on axis at 10m from the source - displayed in the Point Source Editor - is derived directly from the front part of the directivity balloon and not the average Sound Power File.