Stereo Audio Rotation for Head-Tracking Realism
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Solution Overview
Problem
Current technologies fail to effectively rotate virtual sound sources in response to head movements when using standard two-channel audio, such as binaural recordings, leading to a lack of realism in audio experiences, especially in virtual reality applications where precise sound direction changes are needed.
Innovation Solution
A system that separates and recombines two-channel audio signals to simulate sound sources from different directions based on the listener's head orientation, using a combination of sound source extraction, rotation, and combination processes to maintain sound characteristics and realism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard two-channel binaural recordings are used, then the audio signal can be transmitted and played back through headphones, but the sound sources cannot be effectively rotated in response to head movements
Solution Approach 1:
The patent segments the two-channel audio signal into multiple directional sound sources by analyzing inter-channel time delays and amplitude differences. Each sound source is independently identified and can be individually rotated, allowing the system to adapt to head movements while maintaining the simplicity of two-channel transmission.
Solution Approach 2:
The patent introduces a rotational dimension to the standard two-channel audio playback. By calculating rotation angles based on head movement data and applying spatial transformation matrices, the system adds head-relative orientation capability without requiring additional audio channels, effectively moving from a static 2D stereo field to a dynamic 3D head-centered audio environment.
2Reliability
If multiple microphones and channels are used to create surround sound effects, then realistic 3D surround sound can be achieved, but the system complexity increases
Solution Approach 1:
The patent extracts directional information from standard two-channel binaural recordings by analyzing inter-channel time delays and amplitude relationships. This extraction process recovers spatial characteristics that would normally require multiple microphones, allowing the system to achieve realistic sound direction perception while maintaining compatibility with simple two-channel audio formats.
Solution Approach 2:
The patent creates virtual spatial representations of sound sources by computing their apparent positions based on the stereo signal characteristics. These virtual sound source copies are then rotated in response to head movements, replicating the effect of physical surround sound systems without requiring additional physical microphones or speakers.
3Reliability
If the audio signal is processed to rotate sound sources, then realism is enhanced during head movement, but the processing complexity increases
Solution Approach 1:
The patent performs preliminary analysis of the two-channel audio signal to identify and characterize individual sound sources, storing their directional parameters and characteristics. This pre-processing allows the system to quickly rotate identified sound sources in response to head movements without requiring complex real-time analysis, reducing computational complexity during actual head rotation events.
Solution Approach 2:
The patent replaces complex mechanical multi-channel surround sound systems with computational signal processing methods. By using mathematical transformations on two-channel signals to simulate spatial rotation effects, the system achieves realistic head-tracking audio without the hardware complexity of physical surround sound configurations.
Data Source
AI summary
A system for rotating sound provides for the ability of the apparent direction of sound sources in a listening environment to remain in consistent orientations in space despite rotations of the microphones used to capture the sound and despite rotations of the head of the listener, even when wearing headphones. Modules are provided in the system to distinguish the sound sources and their apparent directions, as well as to rotate the sound sources in response to detected rotations of the listener's head and/or detected rotations of the microphones.