Evaluation of a parametric pinna model for the calculation of head-related transfer functions

Pollack, Katharina; Majdak, Piotr

doi:10.1109/i3da48870.2021.9610885

Cited by 8 publications

(17 citation statements)

References 19 publications

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“…The size, shape, and location of the ear are critical inputs to the design of hearing protection and both in-ear and head-worn audio devices, including headphones, earbuds, and hearing aids (Liu 2008, Ji et al 2018, Lu et al 2021. The size and shape of the ear affects the head-related transfer function (HRTF), which affects the ability of the listener to localize sound (Pollack et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Development of a Parametric Model of Adult Human Ear Geometry

Reed,

Vallier,

Bonifas

2024

Preprint

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Section: Introductionmentioning

confidence: 99%

Development of a Parametric Model of Adult Human Ear Geometry

Reed,

Vallier,

Bonifas

2024

Preprint

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“…This paper is part of a three-paper study in which measured and simulated data on the same outer ear replicas and other individual geometries are analysed [10,11].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Impedance Effects on Head-Related Transfer Functions of 3D Printed Pinna and Ear Canal Replicas

Di Giusto,

Sinev,

Pollack

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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Numerical simulations of Head-Related Transfer Functions (HRTFs) are an efficient method to obtain the binaural filters necessary for spatial audio reproduction. Stateof-the-art simulated HRTFs are generally computed at the blocked ear canal of scanned geometries using rigid acoustic boundary conditions. This choice is justified by measurements of human skin impedance up to 6 kHz, showing an acoustically rigid behaviour. The limited bandwidth of these measurements is due to the difficulty in reliably measuring skin impedance up to the highest audible frequency. Furthermore, rigid boundary conditions can lead to discrepancies between measured and simulated HRTFs at high frequencies. To assess the effect of the outer ear acoustic impedance characteristics on the HRTFs, 3D printed replicas of individual pinna and ear canal geometries are used in this study, allowing the creation of samples which can be characterised in an impedance tube up to high frequencies. Their measured impedance is used as a boundary condition in simulations, which outcomes relate to a lower spectral distortion to measured transfer functions in comparison to rigid computations. The perceptual effect of modelling impedance in the simulations is however found to be minimal.

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“…Even though recent achievements reduced the required measurement time (Majdak et al, 2007;Enzner et al, 2013;Richter, 2019), most measurement systems still rely on rather complex immobile setups, such as (semi-)circular loudspeaker arcs, where a full-spherical coverage of measurement directions needs a continuous rotation of the subject or the installation. Besides measurements, there are also alternative methods to obtain individual HRTFs (Guezenoc and Seguier, 2018), such as numerical simulation from 3D models (Pollack and Majdak, 2021) or individualization of generic HRTFs (Bomhardt, 2017). Even though those methods mostly have some shortcomings compared to measurements, they primarily target a consumer audience, where their simplicity justifies their relevance.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the Optimal Spherical Harmonics Order for the Interpolation of Head-Related Transfer Functions Sampled on Sparse Irregular Grids

Bau

Arend²,

Pörschmann³

2022

Front. Signal Process.

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Conventional individual head-related transfer function (HRTF) measurements are demanding in terms of measurement time and equipment. For more flexibility, free body movement (FBM) measurement systems provide an easy-to-use way to measure full-spherical HRTF datasets with less effort. However, having no fixed measurement installation implies that the HRTFs are not sampled on a predefined regular grid but rely on the individual movements of the subject. Furthermore, depending on the measurement effort, a rather small number of measurements can be expected, ranging, for example, from 50 to 150 sampling points. Spherical harmonics (SH) interpolation has been extensively studied recently as one method to obtain full-spherical datasets from such sparse measurements, but previous studies primarily focused on regular full-spherical sampling grids. For irregular grids, it remains unclear up to which spatial order meaningful SH coefficients can be calculated and how the resulting interpolation error compares to regular grids. This study investigates SH interpolation of selected irregular grids obtained from HRTF measurements with an FBM system. Intending to derive general constraints for SH interpolation of irregular grids, the study analyzes how the variation of the SH order affects the interpolation results. Moreover, the study demonstrates the importance of Tikhonov regularization for SH interpolation, which is popular for solving ill-posed numerical problems associated with such irregular grids. As a key result, the study shows that the optimal SH order that minimizes the interpolation error depends mainly on the grid and the regularization strength but is almost independent of the selected HRTF set. Based on these results, the study proposes to determine the optimal SH order by minimizing the interpolation error of a reference HRTF set sampled on the sparse and irregular FBM grid. Finally, the study verifies the proposed method for estimating the optimal SH order by comparing interpolation results of irregular and equivalent regular grids, showing that the differences are small when the SH interpolation is optimally parameterized.

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Evaluation of a parametric pinna model for the calculation of head-related transfer functions

Cited by 8 publications

References 19 publications

Development of a Parametric Model of Adult Human Ear Geometry

Development of a Parametric Model of Adult Human Ear Geometry

Analysis of Impedance Effects on Head-Related Transfer Functions of 3D Printed Pinna and Ear Canal Replicas

Estimation of the Optimal Spherical Harmonics Order for the Interpolation of Head-Related Transfer Functions Sampled on Sparse Irregular Grids

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