Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics

Expressing head-related transfer functions (HRTFs) in the spherical harmonic (SH) domain has been thoroughly studied as a method of obtaining continuity over space. However, HRTFs are functions not only of direction but also of frequency. This paper presents an extension of the SH-based method, util...

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Main Author: Adam Szwajcowski
Format: Article
Language:English
Published: Institute of Fundamental Technological Research Polish Academy of Sciences 2023-03-01
Series:Archives of Acoustics
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Online Access:https://journals.pan.pl/Content/126391/PDF/aoa.2023.144267.pdf
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author Adam Szwajcowski
author_facet Adam Szwajcowski
author_sort Adam Szwajcowski
collection DOAJ
description Expressing head-related transfer functions (HRTFs) in the spherical harmonic (SH) domain has been thoroughly studied as a method of obtaining continuity over space. However, HRTFs are functions not only of direction but also of frequency. This paper presents an extension of the SH-based method, utilizing hyperspherical harmonics (HSHs) to obtain an HRTF representation that is continuous over both space and frequency. The application of the HSH approximation results in a relatively small set of coefficients which can be decoded into HRTF values at any direction and frequency. The paper discusses results obtained by applying the method to magnitude spectra extracted from exemplary HRTF measurements. The HRTF representations based on SHs and HSHs exhibit similar reproduction accuracy, with the latter one featuring continuity over both space and frequency and requiring much lower number of coefficients. The developed HSH-based continuous functional model can serve multiple purposes, such as interpolation, compression or parametrization for machine-learning applications.
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spelling doaj-art-b6528fb2d1584891a46a677a4d6fe3c32025-08-20T02:54:48ZengInstitute of Fundamental Technological Research Polish Academy of SciencesArchives of Acoustics0137-50752300-262X2023-03-01vol. 48No 1127139https://doi.org/10.24425/aoa.2023.144267Continuous Head-related Transfer Function Representation Based on Hyperspherical HarmonicsAdam Szwajcowski0Department of Robotics and Mechatronics, AGH University of Science and Technology, Kraków, PolandExpressing head-related transfer functions (HRTFs) in the spherical harmonic (SH) domain has been thoroughly studied as a method of obtaining continuity over space. However, HRTFs are functions not only of direction but also of frequency. This paper presents an extension of the SH-based method, utilizing hyperspherical harmonics (HSHs) to obtain an HRTF representation that is continuous over both space and frequency. The application of the HSH approximation results in a relatively small set of coefficients which can be decoded into HRTF values at any direction and frequency. The paper discusses results obtained by applying the method to magnitude spectra extracted from exemplary HRTF measurements. The HRTF representations based on SHs and HSHs exhibit similar reproduction accuracy, with the latter one featuring continuity over both space and frequency and requiring much lower number of coefficients. The developed HSH-based continuous functional model can serve multiple purposes, such as interpolation, compression or parametrization for machine-learning applications.https://journals.pan.pl/Content/126391/PDF/aoa.2023.144267.pdfhyperspherical harmonicshrtfspherical harmonicscontinuous functional modeldirectivity
spellingShingle Adam Szwajcowski
Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics
Archives of Acoustics
hyperspherical harmonics
hrtf
spherical harmonics
continuous functional model
directivity
title Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics
title_full Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics
title_fullStr Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics
title_full_unstemmed Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics
title_short Continuous Head-related Transfer Function Representation Based on Hyperspherical Harmonics
title_sort continuous head related transfer function representation based on hyperspherical harmonics
topic hyperspherical harmonics
hrtf
spherical harmonics
continuous functional model
directivity
url https://journals.pan.pl/Content/126391/PDF/aoa.2023.144267.pdf
work_keys_str_mv AT adamszwajcowski continuousheadrelatedtransferfunctionrepresentationbasedonhypersphericalharmonics