Head-Tracked Spatial Audio via Dynamic Microphone Filtering
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Solution Overview
Problem
Existing spatial audio technologies, such as channel-based, object-based, and scene-based systems, face limitations in accurately rendering sound scenes that adapt to a user's head position, particularly in preserving time and amplitude differences, and often require intermediate formats that can result in information loss.
Innovation Solution
A method that generates and applies spatial filters mapping the response of a microphone array to head-related transfer functions (HRTFs) for various head positions, allowing for continuous head-tracked spatial audio generation directly from microphone signals without intermediate formats, preserving time and amplitude differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If intermediate formats (e.g., Ambisonics or virtual loudspeaker arrays) are used to represent sound scenes, then spatial audio rendering can be achieved, but information loss occurs between pick-up beams
Solution Approach 1:
The patent extracts and preserves the essential spatial information (time and amplitude differences) directly from microphone signals without converting to intermediate formats. By taking out only the necessary spatial characteristics and maintaining them throughout processing, the system avoids the information loss that occurs when converting to and from intermediate representations like Ambisonics or virtual loudspeaker arrays
Solution Approach 2:
The patent introduces spatial filters as an intermediary mechanism that directly maps microphone signals to output channels while preserving spatial characteristics. These spatial filters act as mediators that maintain time and amplitude differences without requiring conversion to intermediate formats, thereby avoiding information loss while managing the complexity of spatial audio rendering
2Adaptability or versatility
If channel-based audio systems are used, then audio capture can be arranged to match speaker layout, but the system is constrained to particular playback setups with specific speaker counts and positions
Solution Approach 1:
The patent creates a universal spatial audio system that can render to any speaker configuration through spatial filters. The same microphone signals can be adapted to different playback setups (stereo, 5.1, 7.1, spatial audio formats) without requiring specific capture arrangements matched to each configuration, making the system versatile across multiple playback scenarios
Solution Approach 2:
The patent employs dynamic spatial filtering that can adapt the audio signal in real-time based on the desired output configuration. The spatial filters dynamically adjust the microphone signals to match any speaker layout, allowing the system to transition between different playback configurations without fixed capture arrangements
3Productivity
If object-based audio is used to manage discrete sound sources, then spatial rendering can be performed, but processing, bandwidth, and memory constraints become impractical when the number of sound sources increases
Solution Approach 1:
The patent merges multiple discrete sound sources into a unified spatial representation captured by the microphone array. Instead of processing each sound source as a separate object, the system captures the combined acoustic scene and applies spatial filters to reproduce the spatial characteristics, significantly reducing processing, bandwidth, and memory requirements while maintaining spatial accuracy
Data Source
AI summary
Spatial filters are generated that map response of an audio capture device to head related transfer functions (HRTFs) for different positions of the audio capture device relative to the HRTFs. A current set of spatial filters are determined based on the plurality of spatial filters and a head position of a user. The microphone signals are convolved with the current set of spatial filters, resulting in a left audio channel and right audio channel that form output binaural audio channels. The binaural audio channels can be used to drive speakers of a headphone set to generate sound that is perceived to have a spatial quality. Other aspects are described and claimed.