Wave Arts Sofa2Pan

Sofa2Pan

Free application to convert SOFA format HRIRs to Panorama format

Sofa2Pan is for Panorama 7 users who may want to import HRIR data in SOFA format. SOFA (Spatially Oriented Format for Acoustics) is a standard file format used for interchange of head-related impulse responses. There are large publicly available sets of binaural responses in SOFA format. Sofa2Pan converts SOFA format HRIR data to Panorama format, and by default leaves the converted HRIR data in the directory that Panorama 7 scans for user HRIRs. Sofa2Pan can be launched from Panorama 7 via the HRIR menu option “Import SOFA data”.

Sofa2Pan uses the NetCDF libraries to read SOFA format data. On Windows, when installing the NetCDF libraries, it’s important to select “Add netCDF to the system PATH for all users”, otherwise Sofa2Pan will not be able to load the NetCDF library.

Conversion is done by selecting locations from the SOFA data to populate the Panorama data. Panorama expects data to be spaced uniformly in azimuth at each elevation, and for elevations to be spaced uniformly. SOFA HRIR data may have some other spatial distribution, and may not extend to all elevations. Sofa2Pan first scans the distribution of locations in the SOFA data and determines the minimum and maximum elevations represented, and also the average angular spacing between locations. It then chooses Panorama compatible elevations and azimuth spacing, and iterates through these. At each elevation and azimuth it selects the closest location in the SOFA data and populates the Panorama data. Hence there may be some location errors but in practice the errors are small and not noticeable during spatialization.

In order for Sofa2Pan to work well, the HRIR data must be reasonably well distributed around the head. If all the sampled locations are on one side of head, or if there are only a handful of locations sampled, the results will not be good.

By default, Sofa2Pan converts the HRIR data to “minimum-phase” responses, separately calculating the interaural time delay. This options sounds best with Panorama when spatializing moving sources.