Source Directivity

[Clarity-Acoustical]

Hello!

I'm looking for more information on setting up source directivity.

For the simulation I'm working on, I need a source with (roughly) a 180 degree horizontal spread, and a ~30-50 degree vertical spread. I did see another post (https://groups.google.com/g/i-simpa-user-forum/c/hNgM9BfOT8M/m/aXTo-k9SBQAJ) which indicated I-Simpa uses the EASE format for user-defined directivities. I found some manufacturer .gll files (i.e., https://vue-audiotechnik.com/downloads-glls/#, and https://jblpro.com/en/support_downloads/download_types/easedatum), however, when I use these files (I have to change the extension from .gll to .txt for I-Simpa to recognize them), the simulation is unable to be completed.

Can anyone provide some information?

Thanks,
Luke

[nicolas-f]

Hi
You have to generate a file with the same format as written in the files located in the I-Simpa installation folder:
Directivities\speaker-test1.txt

This format is defined here:
http://www.olsonsound.com/PDF/EASE%204.0%20Loudspeaker%20Device%20File%20Formats%20v4.04e.pdf

[nicolas-f]

Hi,

In which format is your original directivity file?

[ldaniel-jmz]

I just have the data in a spreadsheet.

[nicolas-f]

As you can see here:
https://github.com/Universite-Gustave-Eiffel/I-Simpa/blob/master/currentRelease/Directivities/speaker-test2.txt
and here (the directivity file reader):
https://github.com/Universite-Gustave-Eiffel/I-Simpa/blob/v1.3.4/src/lib_interface/input_output/directivity/directivityParser.cpp#L69

I-Simpa expect the following line:
"Frequency",40,"Hz"
It reads the frequency number

then for each line it will read the phi number and all attenuation for each theta values (37 * 5° ) 0-185

So you should write a script in order to generate this file from your spreadsheet. And check the orientation with a simulation in SPPS.

[ldaniel-jmz]

I don´t have the knowledge to generate that script, that's why I was trying to use the Excel template that generates the ASCII .xhn directivity files provided by amfg, as you mentioned in a previous discussion I-Simpa uses tabular text format directivity as specified by EASE.

This template is of free-use, and you can download it here.

[fredmzlp]

Hi all,
I am also trying to get a custom directivity pattern to I-Simpa.
By looking at the directivity files on GitHub, and at the format definition pdf (http://www.olsonsound.com/PDF/EASE%204.0%20Loudspeaker%20Device%20File%20Formats%20v4.04e.pdf) a couple questions arise.

The pdf EASE definition of azimuth and elevations quite odd (?). And the way it recommends arranging the data is with theta in rows, going from 0 to 180, and with phi in columns, going from 0 to 355.
Checking the directivity speaker-test3.txt, I notice that rows go from 0 to 355, while columns go from 0 to 180. What is the convention for direction angles applied here?
I would assume that rows from 0 to 355 are azimuth angles (phi), while columns are elevation angles (theta). According to the documentation "Modelling of physical phenomena in SPPS" figure "Elementary geometry for a sound source" this would mean angles (0,0) as direction of z axis (i.e direction pointing to directly above?)
Though, defining an omnidirectional source, further below in the documentation, polar plot of "Distribution of emission angles 𝜃
for an omnidirectional source" seems not compatible to theta defined from 0 to 180, and omnidirectional radiation as a "sphere". I probably am missing something regarding this plot...?

Find figures attached for convenience.

And as a final observation, speaker-test1.txt and speaker-test2.txt files do not have the header columns 0 to 180 angles, as in speaker-test3.txt. Are this not strictly necessary for I-Simpa?

Hoping I was clear enough expressing my questions.
Any contribution is much appreciated

Thanks, Fred