Near-field Binaural Rendering with Distance-Normalized HRTFs
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Solution Overview
Problem
Existing spatial audio technologies struggle to accurately render sound sources in the near-field, as they rely on far-field head-related transfer functions (HRTFs) that do not account for significant interaural HRTF changes at closer distances, leading to inaccuracies in audio simulations, especially in virtual reality and augmented reality applications where objects often occur closer to the user.
Innovation Solution
The method employs multiple sets of HRTFs measured at various distances from a reference head, spanning from the near-field to the far-field, with relative distance-related gains normalized to far-field HRTF gains, allowing for accurate representation of full 3D audio mixes and enabling head tracking, compatibility with existing audio codecs, and support for real-time content production in VR applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If far-field HRTFs are used for spatial audio rendering, then compatibility with existing audio codecs and systems is maintained, but accuracy in rendering near-field sound sources is degraded
Solution Approach 1:
The patent segments the spatial audio rendering process into near-field and far-field components. Multiple sets of HRTFs are measured at different distances (near-field and far-field), and the system selectively applies the appropriate set based on the sound source distance. This segmentation allows accurate near-field rendering while maintaining far-field compatibility with existing systems.
Solution Approach 2:
The patent implements dynamic selection between near-field and far-field HRTF sets based on the distance of the sound source. The system dynamically determines which HRTF set to apply by comparing the sound source distance against a threshold, enabling adaptive rendering accuracy that matches the spatial context while maintaining broad system compatibility.
2Measurement precision
If multiple sets of HRTFs measured at various distances are employed, then near-field spatial audio fidelity is improved, but computational complexity and data requirements increase
Solution Approach 1:
The patent applies partial action by using only two specific sets of HRTFs (near-field and far-field) rather than continuously varying distances. This selective approach provides sufficient accuracy for near-field rendering while avoiding the computational burden of implementing HRTFs for all possible distances, achieving an optimal balance between fidelity and complexity.
Data Source
AI summary
The method and apparatus described herein make use of multiple sets of head related transfer functions (HRTFs) that have been synthesized or measured at various distances from a reference head, spanning from the near-field to the boundary of the far-field. Additional synthetic or measured transfer functions maybe used to extend to the interior of the head, i.e., for distances closer than near-field. In addition, the relative distance-related gains of each set of HRTFs are normalized to the far-field HRTF gains.