Virtual Object Reverberation Using Symmetry Groups and Delay Feedback
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Solution Overview
Problem
Existing methods for generating sound reverberation are computationally expensive and fail to accurately reproduce the characteristics of acoustical spaces such as shape, size, and materiality, while convolution-based approaches are limited by data availability and adaptability.
Innovation Solution
A method that generates a reverberation audio signal by representing a virtual object with symmetry groups of virtual points, determining virtual point and symmetry group audio signals, and combining them to mimic the acoustics of the virtual object, using delay and feedback operations to create a reverberation audio signal that reflects the object's shape, size, and material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tapped delay lines are used to simulate reverberation paths, then accuracy of reverberation simulation is improved, but computational cost increases significantly
Solution Approach 1:
The patent segments the reverberation simulation into two distinct parts: early reflections (discrete, deterministic paths) and late reverberation (stochastic, dense reflections). Early reflections are simulated using a limited number of tapped delay lines corresponding to specific geometric paths, while late reverberation is generated using a stochastic process with a single feedback delay line. This segmentation allows accurate simulation of perceptually important early reflections without the computational burden of simulating all individual late reflections.
Solution Approach 2:
The patent replaces the computationally expensive approach of using many tapped delay lines for late reverberation with a much simpler stochastic process. Instead of maintaining numerous persistent delay lines, the system uses a single feedback delay line with random modulation to generate late reverberation, dramatically reducing computational requirements while maintaining perceptual quality.
2Measurement precision
If point-to-point transfer functions are used for each source and listener position, then accuracy of spatial reverberation is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal reverberation algorithm that works for any source and listener positions without requiring separate point-to-point transfer functions. The stochastic late reverberation generator produces spatially distributed reflections that are valid for all positions within the acoustic space, eliminating the need for multiple position-specific simulations while maintaining spatial accuracy.
Solution Approach 2:
The patent introduces dynamic elements to the reverberation system, including time-varying modulation of the feedback delay line and adaptive control of reflection parameters. This allows the system to adapt to different source and listener positions dynamically rather than requiring pre-computed static transfer functions for each position pair.
3Measurement precision
If spatialization of reflections is implemented for 3D positioning, then perceptual accuracy is improved, but computational load increases
Solution Approach 1:
The patent segments spatial processing into early reflections (which require explicit spatialization for each discrete path) and late reverberation (which uses a stochastic spatial distribution). This allows computationally intensive spatial processing only where perceptually necessary, while using simpler stochastic spatialization for the dense late reverberation field.
Solution Approach 2:
The patent uses parameter modulation in the stochastic late reverberation generator to control spatial distribution characteristics. By changing parameters such as modulation depth, frequency, and distribution patterns, the system achieves perceptually accurate spatialization without requiring complex real-time calculations for each reflection path.
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
The method efficiently reproduces the characteristics of acoustical spaces in real-time, allowing adaptability and flexibility in virtual environments, while minimizing computational resources and requiring fewer delay lines.
Implementation Method 1
determining a time delay associated with propagating sound from the virtual sound source to the virtual point
Implementation Method 2
determining, based on the composite audio signal and the determined time delay, a feedback audio signal
Data Source
AI summary
Generating a reverberation audio signal associated with a virtual object comprises storing a representation of the virtual object defining a plurality of virtual points constituting the virtual object that have respective virtual positions with respect to each other, and belong to symmetry groups of virtual points, which is associated with a set of symmetry group distance(s), which sets are respectively associated with symmetry groups, together forming a further set of distance(s). An input audio signal is obtained, and, for each virtual point, a virtual point audio signal component is determined, the virtual point audio signal components are combined to obtain a composite audio signal. Each, distinct distance in the further set of one or more distances is determined based on the composite audio signal and distance audio signal(s). The reverberation audio signal is based on the distance audio signal(s) and the virtual point audio signal components.