Virtual Audio Rendering With Multi-Sector Crosstalk Cancellation

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Solution Overview

Problem

Existing virtual spatial audio rendering systems are highly dependent on the listener being in the optimal position relative to the speakers, compromising the spatial impression for listeners outside the 'sweet spot' and limiting the effectiveness of crosstalk cancellation.

Innovation Solution

The method involves panning the binaural signal generated from each audio object between multiple crosstalk cancellers, each designed for different physical locations and orientations, and an improved equalization scheme to maintain spatial impression and timbre consistency across various listener positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single pair of speakers with crosstalk cancellation is used, then spatial audio rendering is achieved, but the spatial impression deteriorates for listeners outside the sweet spot

Engineering Contradiction:
Improvespatial impression accuracyVSAvoidlistener position adaptability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent divides the audio rendering system into multiple independent crosstalk canceller units, each responsible for a specific spatial sector. Instead of using one universal crosstalk canceller for all directions, the system segments the 360-degree spatial environment into multiple sectors, with each sector having its own optimized crosstalk canceller. This segmentation allows each unit to be precisely tuned for its specific directional range, maintaining spatial accuracy while covering the entire surround environment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single stereo pair configuration to a multi-pair spatial arrangement, adding dimensional complexity to the speaker configuration. By distributing multiple speaker pairs around the listener in different spatial positions and orientations, the system creates a multi-dimensional audio field that can accommodate listeners at various positions, effectively solving the sweet spot limitation through spatial dimensionality.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If multiple speaker pairs are used to expand the sweet spot, then listener position adaptability improves, but device complexity increases

Engineering Contradiction:
Improvelistener position adaptabilityVSAvoidspeaker system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a modular system where each crosstalk canceller unit can serve multiple functions. Each unit is designed to handle both crosstalk cancellation and spatial rendering simultaneously, and can be activated or deactivated based on the listener's position. This multi-functionality reduces the need for entirely separate systems for different listening scenarios, thereby managing complexity while maintaining adaptability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically selects and activates appropriate crosstalk canceller units based on the detected listener position. Rather than all speaker pairs operating at full complexity simultaneously, the system adapts its configuration in real-time, activating only the necessary units for the current listening scenario. This dynamic operation reduces effective complexity while maintaining high adaptability across different positions.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If crosstalk cancellation is applied, then spatial audio accuracy improves, but timbre consistency deteriorates for off-center listeners

Engineering Contradiction:
Improvespatial audio accuracyVSAvoidtimbre consistency
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent applies different crosstalk cancellation characteristics to different spatial sectors rather than using a uniform approach. Each crosstalk canceller unit is optimized with specific filter characteristics tailored to its local spatial region and the typical listener positions within that sector. This local optimization ensures that spatial accuracy is maintained in each sector while minimizing timbre distortion for listeners in those specific regions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts the parameters of the crosstalk cancellation filters based on the listener's position and the active speaker pair configuration. By changing filter parameters such as cancellation depth, frequency response, and spatial weighting in real-time, the system maintains both spatial accuracy and timbre consistency across different listening positions, adapting the cancellation characteristics to match the current spatial geometry.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2891336B1Virtual rendering of object-based audio
Publication Date: 2017.10.04 DOLBY LABORATORIES LICENSING CORP
  • EP2891336B1 patent drawingFigure 1
  • EP2891336B1 patent drawingFigure 2
  • EP2891336B1 patent drawingFigure 3

AI summary

Embodiments are described for a system for virtual rendering of object based audio through binaural rendering of each object followed by panning of the resulting stereo binaural signal between a plurality of cross-talk cancelation circuits feeding a corresponding plurality of speaker pairs. In comparison to prior art virtual rendering utilizing a single pair of speakers, the described embodiments improve the spatial impression for both listeners inside and outside of the cross-talk canceller sweet spot. Also described is an improved equalization technique for a crosstalk canceller that is computed from both the crosstalk canceller filters and the binaural filters and applied to a monophonic audio signal being virtualized. The described technique improve timbre for listeners outside of the sweet-spot as well as a smaller timbre shift when switching from standard rendering to virtual rendering.