Efficient representation of head-related transfer functions using spatially oriented format for acoustics

P Majdak, H Ziegelwanger, H Wierstorf, M Noisternig, "Efficient representation of head-related transfer functions using spatially oriented format for acoustics," in Proceedings of the 21st International Congress on Sound and Vibration (ICSV), (2014). [ paper ]

Bibtex

@inproceedings{Majdak2014,
    title     = {Efficient representation of head-related transfer functions
                 using spatially oriented format for acoustics},
    author    = {Majdak, Piotr and Ziegelwanger, Harald and Wierstorf, Hagen
                 and Noisternig, Markus},
    booktitle = {Proceedings of the 21st International Congress on Sound and
                 Vibration (ICSV)},
    address   = {Beijing, China},
    month     = {July},
    year      = {2014}
}

Abstract

Head-related transfer functions (HRTFs) describe the spatial filtering of the incoming sound by the head, pinna, and torso of a listener. Transformed to the time domain, HRTFs are referred to as head-related impulse responses (HRIRs). While usually measured under free-field conditions, HRIRs are referred to as binaural room impulse responses (BRIRs) when room effects are considered additionally. HRIRs and BRIRs have been measured by a number of laboratories and are usually stored using the labs’ own file formats, which often complicates the exchange of data due to format incompatibilities. Recently, the “spatially oriented format for acoustics” (SOFA) has been proposed to unify the representation of such data. SOFA provides data compression, network transfer, file hierarchy, and possibility for a link to complex room geometry data. SOFA specifications allow to develop application programming interfaces (APIs) for various programming languages; current implementations include Matlab and Octave. Within SOFA, the different types of data are represented by different conventions, i.e., defined sets of variables and attributes. In this contribution, we introduce the general SOFA specifications and describe SOFA conventions allowing to store HRIRs. Currently, in the SOFA database, eight large databases have been unified offering HRIRs/BRIRs of over 200 listeners stored in the same format.

Supplementary material

The SOFA HRTF format has become an AES standard in the meantime, see http://www.aes.org/publications/standards/search.cfm?docID=99

For more information on the format and available data bases, see https://www.sofaconventions.org

API implementations in Matlab/Octave and C++ can be found at https://github.com/sofacoustics

Two example applications using the API and providing more functionality like getting the impulse response for a particular listening position and direction are the Two!Ears Binaural Simulator and the Sound Field Synthesis Toolbox, in particular get_ir().