Spherical Harmonics Based HRTF Datasets: Implementation and Evaluation for Real-Time Auralization

Richter, Jan-Gerrit; Pollow, Martin; Wefers, Frank; Fels, Janina

doi:10.3813/aaa.918746

Cited by 10 publications

(9 citation statements)

References 9 publications

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“…2 shows the accuracy of each pipeline as a function of the number of kernels, K. For each metric, when a relatively small number of kernels (K < 20) is used, the time-aligned methods outperform their conventional counterparts. This is consistent with previously reported results [18,20]. As more components are used the conventional methods perform better whereas the worst case error for GDA VBAP and GDA SH plateaus.…”

Section: Discussionsupporting

confidence: 93%

“…This is a time-aligned version of vector base amplitude panning (VBAP) [17] and we present a more efficient structure below in which delays are introduced before the convolution step. In [18] spherical harmonic (SH) interpolation of HRIRs was used to obtain time varying filters for dynamic spatialization. It was shown that more of the energy in the SH representation is concentrated at lower orders if the SH expansion is performed around microphonecentred co-ordinates.…”

Section: Introductionmentioning

confidence: 99%

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Processing Pipelines for Efficient, Physically-Accurate Simulation of Microphone Array Signals in Dynamic Sound Scenes

Moore

Vos

Naylor

et al. 2021

ICASSP 2021 - 2021 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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Multichannel acoustic signal processing is predicated on the fact that the interchannel relationships between the received signals can be exploited to infer information about the acoustic scene. Recently there has been increasing interest in algorithms which are applicable in dynamic scenes, where the source(s) and/or microphone array may be moving. Simulating such scenes has particular challenges which are exacerbated when real-time, listener-in-the-loop evaluation of algorithms is required. This paper considers candidate pipelines for simulating the array response to a set of point/image sources in terms of their accuracy, scalability and continuity. A new approach, in which the filter kernels are obtained using principal component analysis from time-aligned impulse responses, is proposed. When the number of filter kernels is ≤ 40 the new approach achieves more accurate simulation than competing methods.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Processing Pipelines for Efficient, Physically-Accurate Simulation of Microphone Array Signals in Dynamic Sound Scenes

Moore

Vos

Naylor

et al. 2021

ICASSP 2021 - 2021 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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“…As shown by Duraiswaini and colleagues as well as Richter and colleagues [23], [24], the spherical harmonic decomposition could be used to interpolate HRTF datasets. To this end, each frequency bin from all measured directions could be regarded as a frequency dependent directivity, measured on a spherical surface.…”

Section: Interpolationmentioning

confidence: 99%

Experiments on localization accuracy with non-individual and individual HRTFs comparing static and dynamic reproduction methods

Oberem

Setzer

Koch

et al. 2020

Preprint

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Binaural reproduction can be used in listening experiments under real-life conditions to achieve a high realism and good reproducibility. In recent years a clear trend to more individual reproduction can be observed as the ability to measure individual head-related-transfer-functions (HRTFs) is becoming more widespread. The question of the accuracy and reproduction methods needed for a realistic playback however has not been sufficiently answered. To evaluate an appropriate approach for binaural reproduction via headphones different head-related-transfer-functions (HRTFs) and reproduction methods were compared in this paper. In a listening test eleven explicitly trained participants were asked to localize eleven sound sources positioned in the right hemisphere using the proximal pointing method. Binaural stimuli based on individually measured HRTFs were compared to those of an artificial head in a static reproduction of stimuli and in three dynamic reproduction methods of different resolutions (5 • , 2.5 • and 1 • ). Unsigned errors in azimuth and elevation as well as front-back-confusions and in-head-localization were observed. Dynamic reproduction of any resolution applied turned out fundamental for a reduction of undesired front-back-confusions and in-head-localization. Individually measured HRTFs showed a smaller effect on localization accuracy compared to the influence of dynamic sound reproduction. They were mainly observed to reduce the front-back-confusion rate.

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“…Future work will look at adapting the AIO algorithm to implement frequency-dependent gains for each loudspeaker instead of a single gain as is the current case. Planned subsequent work will also look at integrating the presented AIO method with other pre-processing techniques for improving high-frequency reproduction of binaural Ambisonic rendering using virtual loudspeakers, such as diffuse-field equalization [59], direction-bias equalization [58] and time-alignment [25][26][27]. Preliminary tests have shown that combining AIO with these equalization methods can produce even greater improvements to high-frequency reproduction, and possibly allow for the perceptual experience of a higher Ambisonic order without an increase in convolutions.…”

Section: Discussionmentioning

confidence: 99%

“…Some recent methods for binaural Ambisonic rendering have moved away from the virtual loudspeaker approach and instead focused on order truncation of an approximately spatially continuous spherical harmonic (SH) represented HRIR dataset [21,22]. However, this causes severe high-frequency roll-off at low truncation orders, which requires compensation through pre-processing techniques [23] such as equalization [24], time-alignment [25][26][27] and more recently magnitude least squares [28]. As this also requires a highly dense dataset of HRIRs measured at points on the sphere distributed by a regular (or at least semi-regular) quadrature such as the Lebedev grid [29], it is, therefore, considered infeasible for individualization at present, despite techniques such as reciprocity [30] and multiple swept sine [31] offering faster measurement times.…”

Section: Introductionmentioning

confidence: 99%

Interaural Level Difference Optimization of Binaural Ambisonic Rendering

2019

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Ambisonics is a spatial audio technique appropriate for dynamic binaural rendering due to its sound field rotation and transformation capabilities, which has made it popular for virtual reality applications. An issue with low-order Ambisonics is that interaural level differences (ILDs) are often reproduced with lower values when compared to head-related impulse responses (HRIRs), which reduces lateralization and spaciousness. This paper introduces a method of Ambisonic ILD Optimization (AIO), a pre-processing technique to bring the ILDs produced by virtual loudspeaker binaural Ambisonic rendering closer to those of HRIRs. AIO is evaluated objectively for Ambisonic orders up to fifth order versus a reference dataset of HRIRs for all locations on the sphere via estimated ILD and spectral difference, and perceptually through listening tests using both simple and complex scenes. Results conclude AIO produces an overall improvement for all tested orders of Ambisonics, though the benefits are greatest at first and second order.

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Spherical Harmonics Based HRTF Datasets: Implementation and Evaluation for Real-Time Auralization

Cited by 10 publications

References 9 publications

Processing Pipelines for Efficient, Physically-Accurate Simulation of Microphone Array Signals in Dynamic Sound Scenes

Processing Pipelines for Efficient, Physically-Accurate Simulation of Microphone Array Signals in Dynamic Sound Scenes

Experiments on localization accuracy with non-individual and individual HRTFs comparing static and dynamic reproduction methods

Interaural Level Difference Optimization of Binaural Ambisonic Rendering

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