Virtual Loudspeaker Alignment for Seamless Spatial Audio

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Solution Overview

Problem

Existing methods for rendering spatially-bounded audio elements with interior and exterior representations suffer from abrupt transitions and unwanted frequency cancellations due to cross-fading between these representations, leading to audible artifacts like comb-filtering effects.

Innovation Solution

Align the positions of virtual loudspeakers used for interior and exterior representations within a transition region, reusing a subset of speakers for both, and smoothly interpolate their positions and signals to ensure seamless transitions without increasing the number of loudspeakers or causing artifacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If cross-fading is used between interior and exterior audio representations, then transition smoothness is improved, but comb-filtering artifacts and frequency cancellations occur

Engineering Contradiction:
Improvetransition smoothnessVSAvoidcomb-filtering artifacts
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediary mechanism by aligning virtual loudspeaker positions between interior and exterior representations. Instead of directly cross-fading unaligned speakers, the system uses aligned speaker positions as an intermediary state, where speakers are positioned at the same spatial locations for both representations during transition, thereby avoiding comb-filtering artifacts while maintaining smooth transitions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple virtual loudspeakers are used for interior and exterior representations, then audio coverage is improved, but device complexity increases

Engineering Contradiction:
Improveaudio coverageVSAvoidnumber of loudspeakers
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the interior and exterior loudspeaker sets by aligning their positions in space. During transition, speakers from both representations are positioned at the same locations, allowing the system to reuse the same physical loudspeakers for both representations simultaneously. This merging approach maintains comprehensive audio coverage while avoiding the need to double the number of physical loudspeakers.

Inventive Principle:
Principle #5Merging (Combining)

3Object-generated harmful factors

If speaker positions are aligned between interior and exterior representations, then transition artifacts are eliminated, but positioning precision requirements increase

Engineering Contradiction:
Improvetransition artifactsVSAvoidspeaker positioning precision
Core Design Contradiction:
Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent uses the exterior loudspeaker configuration as a template or copy for positioning the interior loudspeakers. By copying the spatial positions of exterior speakers to define interior speaker positions during alignment, the system achieves precise positioning without requiring independent high-precision positioning systems for each representation. This copying approach simplifies the precision requirements while eliminating positioning mismatches.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP4179738B1Seamless rendering of audio elements with both interior and exterior representations
Publication Date: 2025.09.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4179738B1 patent drawingFigure 1
  • EP4179738B1 patent drawingFigure 2
  • EP4179738B1 patent drawingFigure 3

AI summary

A method (700) for spatial audio rendering of an audio element having an extent (101). The method includes determining (s702) that a listener is within a transition region that is outside of the extent. The method also includes determining (s704) a first interior rendering with an interior set of virtual loudspeakers. The method also includes determining (s706) an exterior rendering with an exterior set of virtual loudspeakers, wherein the exterior set of virtual loudspeakers comprises first and second virtual loudspeakers. The method also includes, in response to determining that the listener is within the transition region, determining (s708) a transition rendering, wherein the transition rendering includes the interior set of virtual loudspeakers with two loudspeakers in the interior set of virtual loudspeakers replaced by third and fourth virtual loudspeakers, the third and fourth virtual loudspeakers being based on the first and second virtual loudspeakers of the exterior set of virtual loudspeakers. The method also includes rendering (s710) the transition rendering for the listener.