Spatial Reverberation Rendering Through Delay-Diverse FDN Channels
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Solution Overview
Problem
Existing methods for spatially rendering reverberation in augmented and virtual reality systems often fail to produce a perception of fully surrounding and enveloping reverberation, with sound images collapsing into specific directions, and are computationally inefficient, particularly when using feedback delay network (FDN) reverberators.
Innovation Solution
The method involves using a computationally efficient FDN reverberator with channels ordered by delay-line lengths, distributing these channels to spatial positions far apart, and applying directional filters to generate reverberated audio signals that are perceived as surrounding and enveloping, utilizing a feedback delay network (FDN) reverberator with channels having different delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If FDN reverberator channels are assigned to spatial positions without considering delay-line lengths, then the system is simpler to implement, but sound images collapse into specific directions and lose spatial envelopment
Solution Approach 1:
The patent applies local quality by assigning different spatial positions to reverberator channels based on their delay-line lengths. Channels with similar delay lengths are distributed to spatial positions far apart from each other, while channels with different delay lengths are assigned to different spatial positions. This creates locally optimized spatial distribution that prevents sound image collapse and maintains spatial envelopment.
Solution Approach 2:
The patent implements preliminary action by pre-ordering the reverberator channels based on delay-line lengths before assigning them to spatial positions. This pre-sorting ensures that when channels are distributed to spatial positions, those with similar delays are separated, preventing directional collapse before the actual sound reproduction occurs.
2Device complexity
If multiple reverberator channels are assigned to the same spatial position, then the system uses fewer loudspeakers, but the reverberation perception becomes less surrounding and enveloping
Solution Approach 1:
The patent applies local quality by strategically assigning multiple reverberator channels to different spatial positions based on their delay characteristics. This ensures that even when multiple channels are used, they are distributed to create a surrounding sound field rather than collapsing into a single direction, maintaining spatial envelopment quality.
Solution Approach 2:
The patent utilizes spatial position as an additional dimension for channel assignment. Instead of only considering the number of channels or loudspeakers, it introduces the spatial distribution dimension, ordering channels by delay-line lengths and assigning them to spatial positions that maximize separation. This dimensional approach creates a three-dimensional sound field that maintains envelopment even with limited loudspeaker count.
3Device complexity
If channels with similar delay lengths are assigned to adjacent spatial positions, then the implementation is simpler, but the reverberation lacks spatial distribution and sounds directional
Solution Approach 1:
The patent applies local quality by assigning channels with similar delay lengths to spatial positions that are far apart from each other, rather than adjacent positions. This creates a non-uniform spatial distribution where channels with comparable delays are separated, preventing directional bias and enhancing the surrounding reverberation perception.
Solution Approach 2:
The patent introduces asymmetry in the channel-to-spatial-position mapping by deliberately avoiding uniform or adjacent assignments. Instead, it creates an asymmetric distribution where channels are assigned based on their delay characteristics, with similar-delay channels separated by large spatial distances. This asymmetric approach prevents predictable directional patterns and creates more natural-sounding spatial reverberation.
Data Source
AI summary
An apparatus for applying reverberation to at least one audio signal, the apparatus including circuitry configured to: obtain the at least one audio signal; obtain a number of sound reproduction positions for playback audio in relation to a listening position; determine a reverberator including a number of channels, wherein the number of channels is configured with at least two respective delay lines having different delays; assign the reverberator channels to the sound reproduction positions based on the delays of the number of channels; and process the at least one audio signal with the reverberator based on the assigned channels to generate reverberated playback audio signals for the listening position.