Digital Reverberator Startup Control for Early Echo Suppression
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Solution Overview
Problem
Current methods for rendering reverberation in virtual and augmented reality struggle with effectively suppressing early echoes from feedback delay networks (FDN) to minimize interference with separately-rendered early reflections, leading to computational complexity and configuration difficulties.
Innovation Solution
A method and apparatus that control the startup behavior of a digital reverberator using a feedback network with a first echo suppressor, comprising control delay lines and gain filters, to attenuate early echoes and reduce interference with early reflections, thereby improving the interaction between late reverberation and early reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a feedback delay network (FDN) is used to generate reverberation, then the reverberation can be produced with shared acoustic characteristics across channels, but early echoes interfere with separately-rendered early reflections
Solution Approach 1:
The patent segments the reverberation signal processing into distinct paths: one for generating early reflections and another for generating late reverberation through the FDN. By separating the treatment of early echoes from late reverberation, the system can suppress early echoes specifically without affecting the overall reverberation characteristics. This segmentation allows independent control of different reverberation phases.
Solution Approach 2:
The patent extracts and removes early echoes from the FDN output before combining with late reverberation. By identifying and separating the harmful early echo components from the useful late reverberation, the system can selectively attenuate only the interfering early echoes while preserving the desired reverberation effect. This extraction approach targets the specific problematic component without discarding the entire reverberation signal.
2Object-affected harmful factors
If control delay lines and gain filters are added to suppress early echoes, then interference with early reflections is reduced, but device complexity increases
Solution Approach 1:
The control delay lines and gain filters are designed to serve multiple functions: they suppress early echoes, enable smooth transitions between early reflections and late reverberation, and maintain compatibility with the existing FDN structure. By making these control elements multi-functional, the patent reduces the need for additional separate components, thereby managing complexity while achieving multiple objectives.
Solution Approach 2:
The control delay lines act as intermediary elements between the FDN output and the final reverberation signal. These intermediaries provide a controlled interface for suppressing early echoes without directly modifying the core FDN structure. By introducing these intermediary control elements, the system achieves echo suppression while maintaining modularity and managing overall system complexity.
3Stability of the object's composition
If late reverberation is generated with the same acoustic characteristics as early reflections, then the reverberation is perceived as uniform in all directions, but the transition between early reflections and late reverberation becomes abrupt
Solution Approach 1:
The patent introduces dynamic control of the transition between early reflections and late reverberation through the control delay lines and gain filters. Rather than using a static, uniform reverberation characteristics across all channels, the system dynamically adjusts the mixing and timing of early echoes and late reverberation to create a smooth, natural-sounding transition. This dynamic approach allows the reverberation profile to evolve over time, improving perceptual continuity.
Solution Approach 2:
The control delay lines are configured to preliminarily process the FDN output by suppressing early echoes before the late reverberation fully develops. This preliminary action prepares the signal for a smoother transition by removing interfering early components in advance, allowing the late reverberation to blend more naturally with the early reflections without abrupt changes in the temporal evolution of the reverberation field.
Data Source
AI summary
A method for applying reverberation to at least one audio signal, the method including: obtaining the at least one audio signal; obtaining at least one reverberation parameter; controlling a digital reverberator based on the at least one reverberation parameter; providing at least one control line including a delay line and a gain filter, the at least one control line using the at least one reverberation parameter to generate an output from the at least one control line; and generating at least one reverberated audio signal based on at least one output of the at least one digital reverberator and the generated output from the at least one control line, wherein at least a portion of late reverberation in the generated at least one reverberated audio signal interfering with at least one reflection echo is substantially attenuated.