Spatial Audio Rendering with Head Tracking
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Solution Overview
Problem
Existing methods for updating a sound field with spatial information to compensate for user movement are computationally expensive and unsuitable for applications with multiple virtual sources, especially in gaming scenarios, and often result in impaired distance cues and directional localization accuracy due to sub-optimal speaker configurations.
Innovation Solution
A method that determines the location of virtual sources relative to the user and applies a panning function to signal components based on user movement, using a formula that adjusts the gain of each virtual loudspeaker feed according to its angular position and the order of the panning function, allowing for efficient updating of the sound field without re-convolving Head Related Impulse Responses (HRIRs) with the virtual source signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the sound field is updated by detecting head orientation changes and re-calculating the 3-dimensional sound field for new virtual source locations, then the sound field stability is improved, but the computational cost increases significantly
Solution Approach 1:
The patent segments the sound field update process into two distinct stages: an offline pre-computation stage where impulse responses are calculated and stored for various head orientations, and an online runtime stage where pre-computed data is retrieved and combined based on actual head position. This segmentation moves the computationally expensive operations to offline processing, making real-time updates feasible.
Solution Approach 2:
The patent performs preliminary computation of impulse responses for multiple predetermined head orientations before runtime operation. By pre-calculating and storing these impulse responses, the system avoids performing expensive computations during real-time interaction, thereby reducing computational burden while maintaining sound field stability.
2Device complexity
If amplitude panned sound sources are used to rotate the sound field according to user movement, then the device complexity is reduced, but the directional localization accuracy and distance cues are impaired
Solution Approach 1:
The patent introduces pre-computed impulse responses as an intermediary between the simple amplitude panning approach and the complex full 3D sound field recalculation. These impulse responses, stored in lookup tables, contain pre-calculated spatial transformation data that preserves accurate directional cues and distance information while avoiding real-time complex computations.
Solution Approach 2:
The patent changes the approach from directly manipulating amplitude parameters to using pre-computed impulse response parameters that encode complete spatial transformation information. By switching from simple gain adjustments to using pre-calculated convolution kernels, the system maintains high localization accuracy while reducing computational complexity at runtime.
3Measurement precision
If the original signal and current spatial location of each virtual source are accessed to update the sound field, then the sound field accuracy is improved, but the computational burden increases
Solution Approach 1:
The patent extracts the computationally intensive parts of the sound field update process (impulse response calculation) and separates them from the runtime operation. By taking out the heavy computation and performing it offline, the runtime system only needs to perform lightweight operations like retrieving pre-computed data and applying simple convolutions, thereby maintaining accuracy while reducing computational burden.
Data Source
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AI summary
A method of providing an audio signal comprising spatial information relating to a location of at least one virtual source (202) in a sound field with respect to a first user position comprises obtaining a first audio signal comprising a plurality of signal components, each of the signal components corresponding to a respective one of a plurality of virtual loudspeakers (200a-e) located in the sound field; obtaining an indication of user movement; determining a plurality of panned signal components by applying, in accordance with the indication of user movement, a panning function of a respective order to each of the signal components; and outputting a second audio signal comprising the panned signal components.