Multi-Channel Audio Segmentation for Wider, Undistorted Spatial Sound

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Solution Overview

Problem

Portable devices with closely spaced loudspeakers struggle to reproduce a wide spatial audio image due to distortion and reduced dynamic range when applying stereo widening techniques, leading to softer and distorted sound, and degradation of central audio content engagement and timbre.

Innovation Solution

A method and apparatus that process multi-channel audio signals by deriving coherent and non-coherent sound components, applying stereo widening only to non-coherent components, and combining them to create a partially extended spatial audio image, ensuring the central audio content remains clear and undistorted.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If stereo widening techniques are applied to multi-channel audio signals on portable devices, then the spatial audio image width is enhanced, but the dynamic range is reduced and distortion increases

Engineering Contradiction:
Improvespatial audio image widthVSAvoidsound quality (distortion and dynamic range)
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The audio signal is segmented into two distinct components: a first signal component representing coherent sounds within a focus range (central audio content), and a second signal component representing coherent sounds outside the focus range and non-coherent sounds (spatial background). This segmentation allows different processing strategies to be applied to each component, preserving the quality of central content while enhancing spatial width through stereo widening applied only to the second component.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If stereo widening is applied to enhance spatial audio image, then the perceivable width is widened, but the central audio content engagement and timbre are degraded

Engineering Contradiction:
Improvespatial audio image widthVSAvoidcentral audio content engagement and timbre
Core Design Contradiction:
Area of stationary objectVSLoss of information

Solution Approach 1:

Different processing qualities are applied to different spatial regions of the audio signal. The first signal component (central focus range) is processed with high fidelity to preserve engagement and timbre, while the second signal component (peripheral regions) undergoes stereo widening to expand spatial width. This local differentiation of processing quality ensures that central content maintains its original characteristics while the overall spatial image is widened.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3881566B1Audio processing
Publication Date: 2025.09.10 NOKIA TECHNOLOGIES OY
  • EP3881566B1 patent drawingFigure 1A
  • EP3881566B1 patent drawingFigure 1B
  • EP3881566B1 patent drawingFigure 2

AI summary

According to an example embodiment, a technique for processing an input audio signal (101) comprising a multi-channel audio signal is provided, the technique comprising: deriving (104), based on the input audio signal (101), a first signal component (105-1) comprising a multi-channel audio signal that represents a focus portion of a spatial audio image conveyed by the input audio signal and a second signal component (105-2) comprising a multi-channel audio signal that represents a non- focus portion of the spatial audio image; processing (112) the second signal component (105-2) into a modified second signal component (113) wherein the width of the spatial audio image is extended from that of the second signal component (105-2); and combining (114) the first signal component (105-1) and the modified second signal component (112) into an output audio signal (115) comprising a multi- channel audio signal that represents partially extended spatial audio image.