Decoupled Binaural Rendering for VR Audio
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Solution Overview
Problem
Conventional binaural rendering techniques in virtual reality fail to accurately represent non-equidistant audio sources due to significant differences in distance between the effective source on a sphere and each ear of the listener, requiring excessive computational resources and many distance-dependent Head Related Transfer Functions (HRTFs).
Innovation Solution
The method involves generating separate virtual audio locations on a sphere for each ear of the listener, allowing for more accurate representation of actual audio sources by placing virtual loudspeakers at the sphere intersections for each ear, minimizing computational resources and using ambisonic audio decoding to model sound propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional binaural rendering uses a single effective source on a sphere for both ears, then device complexity is reduced, but measurement precision of audio source representation deteriorates due to significant distance differences between the effective source and each ear
Solution Approach 1:
The patent segments the single effective source into separate virtual sources for each ear. Instead of using one common effective source location on the sphere, the system generates distinct virtual sources positioned at locations optimized for left ear and right ear respectively. This segmentation allows each ear to have an accurate representation of the audio source at its specific distance and angle, resolving the contradiction between precision and complexity by tailoring the source representation to each ear's geometry.
Solution Approach 2:
The patent applies local quality by creating ear-specific virtual sources with properties tailored to each ear's position. The left ear receives a virtual source optimized for its distance and angle from the audio source, while the right ear receives a different virtual source optimized for its geometry. This local optimization maintains high measurement precision for each ear without requiring excessive computational resources, as each virtual source is independently optimized rather than using a single global effective source.
2Measurement precision
If distance-dependent HRTFs are used for each ear to accurately represent non-equidistant sources, then measurement precision improves, but device complexity and computational cost increase excessively
Solution Approach 1:
The patent changes the parameters of the virtual sources based on ear-specific geometry. Instead of using a fixed set of distance-dependent HRTFs for all sources, the system dynamically adjusts the virtual source parameters (position, elevation, azimuth) according to each ear's specific relationship to the audio source. This parameter adaptation allows accurate sound field reproduction for non-equidistant sources while avoiding the need to maintain extensive libraries of distance-dependent HRTFs, thus reducing device complexity.
Solution Approach 2:
The patent introduces dynamics by making the virtual source positions adaptive rather than static. The virtual sources are generated dynamically based on the listener's position, head orientation, and the audio source location. This dynamic generation of ear-specific virtual sources allows the system to accurately represent non-equidistant sources in real-time without requiring pre-computed distance-dependent HRTFs for every possible configuration, thereby reducing computational cost and device complexity.
3Measurement precision
If separate virtual sources are generated for each ear, then measurement precision of audio source representation improves, but device complexity increases due to additional processing
Solution Approach 1:
The patent applies preliminary action by pre-establishing the geometric relationships and transformation rules for generating virtual sources. The system pre-defines the mathematical relationships between audio source positions, listener head geometry, and virtual source locations. This preliminary setup allows the actual virtual source generation to proceed efficiently during runtime, as the computational steps are predetermined and optimized. The precision improvement from separate virtual sources is achieved without excessive complexity because the generation process follows pre-established geometric principles.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a more accurate representation of actual audio sources with ambisonic audio at a minimal computational cost, enhancing audio reproduction in virtual reality environments.
Implementation Method 1
performing a first convolution operation on the first sound field and a left head-related transfer function (HRTF) associated with the first virtual location to render a left sound field in the left ear of the listener and performing a second convolution operation on the second sound field and a right HRTF associated with the second virtual location to render a right sound field in the right ear of the listener
Data Source
AI summary
Techniques of performing binaural rendering involve generating separate locations of virtual sources on the sphere for each ear of a listener. Along these lines, consider a set of actual audio sources that are not equidistant from a central point. To provide a listener with ambisonic audio, a sphere is defined with the listener at its center. When a source is not on the surface of the sphere, respective rays from the source to each of the listener's ears may not intersect the sphere at the same point. Rather, to provide a more accurate representation of the actual source, virtual loudspeakers are placed at each of the sphere intersections, a first virtual loudspeaker propagating audio to the left ear, a second virtual loudspeaker propagating audio to the right ear.