About Mesh2HRTF

Head-related transfer functions (HRTFs) describe the listener-specific directional filtering of the incoming sound at the entrance of the ear-canal. Since HRTFs are caused by a scattering process, it seems natural to calculate HRTFs numerically by simulating the sound-field scattered by the human head and ear instead of acquiring HRTFs in an acoustical measurement procedure. Different simulation methods for the numerical calculation of HRTFs were investigated and particularly much research effort has been put into the boundary element method (BEM). HRTFs were numerically calculated with the BEM and evaluated in several studies. In most of these studies, researchers either had to use commercial software or to implement the BEM by them- selves. Both cases make the access to the numerical calculation of HRTFs and reproducible research difficult.

Thus, Mesh2HRTF was developed at the Acoustics Research Institute. Mesh2HRTF is an open-source project aiming at providing an easy-to-use software package for the numerical calculation of HRTFs. It targets researchers in the field of binaural audio. In a nutshell, Mesh2HRTF simply reads geometrical data, calculates the corresponding sound field and outputs HRTFs. To support multiple computer platforms, the concept of Mesh2HRTF is to focus on a command-line tool, which forms the numerical core, i.e., an implementation of the 3-dimensional Burton-Miller collocation BEM coupled with the multi-level fast multipole method (ML-FMM), and to provide add-ons for existing cross-platform applications for the preprocessing of geometrical data and for the visualization of results.

Mesh2HRTF was used for the numerical calculation of HRTFs in several studies. Results were evaluated numerically and perceptually.

Simulate

the sound field

By coupling the BEM with the multi-level fast multipole method, Mesh2HRTF is able to simulate the sound field and to calculate HRTFs for the whole audible frequency-range, i.e., for head and pinnae meshes with more than 100 000 triangular elements.

SOFA

Spatially oriented format for acoustics

Mesh2HRTF saves HRTFs and HRIRs as *.sofa files. SOFA is the official standard of the Audio Engineering Society for storing HRTFs.

References

Mesh2HRTF was presented at the 22nd ICSV in Florence:

• Ziegelwanger, H., and Kreuzer, W., Majdak, P. (2015). "Mesh2HRTF: An open-source software package for the numerical calculation of head-related transfer functions," in Proceedings of the 22nd International Congress on Sound and Vibration, Florence, IT.

Mesh2HRTF was used in following publications:

• Ziegelwanger, H., Majdak, P., and Kreuzer, W. (2015). “Numerical calculation of listener-specific head-related transfer functions and sound localization: Microphone model and geometry discretization,” The Journal of the Acoustical Society of America, 138, 208–222. [doi:10.1121/1.4922518]
• Ziegelwanger, H., and Majdak, P. (2014). “Modeling the direction-continuous time-of-arrival in head-related transfer functions,” The Journal of the Acoustical Society of America, 135, 1278–1293. [doi:10.1121/1.4863196]
• Ziegelwanger, H., Majdak, P., and Kreuzer, W. (2014). “Efficient numerical calculation of head-related transfer functions,” in Proceedings of the Forum Acusticum 2014, Krakow, Poland, 1-6. [pdf]
• Ziegelwanger, H., Majdak, P., and Kreuzer, W. (2014). “Non-uniform sampling of geometry for the numeric simulation of head-related transfer functions,” in Proceedings of the 21st International Congress on Sound and Vibration, Beijing, CN. [pdf]
• Ziegelwanger, H., Reichinger, A., and Majdak, P. (2013). “Calculation of listener-specific head-related transfer functions: Effect of mesh quality,” in Proceedings of Meetings in Acoustics, ASA, 050017. [doi:10.1121/1.4799868]