Multichannel Speaker Delay Filter for Off-Center Stereo Consistency

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Solution Overview

Problem

Conventional audio rendering technologies using speaker arrays fail to provide a consistent stereo sound image and sense of presence for listeners positioned off-center, as the effect of the stereo sound image depends on the listener's location.

Innovation Solution

An audio rendering device utilizing multichannel speakers with a first delay computation unit for primary wavefronts and a second delay computation unit for secondary wavefronts, which computes and applies total delays to input audio signals to generate a multichannel audio signal, ensuring a wide stereo sound image and sense of envelopment irrespective of the listener's position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional audio rendering technologies using speaker arrays are used, then the system can generate virtual sources and widen stereo sound images, but the stereo sound image effect and sense of presence depend on the listener's position

Engineering Contradiction:
Improvestereo sound image consistencyVSAvoidlistener position dependency
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The audio signal is segmented into multiple components: primary wavefront signals and secondary wavefront signals (scattered signals). Each component is processed separately with different delay computations, allowing the system to maintain stereo image consistency across different listener positions by reconstructing the complex acoustic field from these segmented components

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from conventional single-wavefront rendering to a multi-dimensional acoustic field synthesis by introducing secondary scattered wavefronts in addition to primary wavefronts. This dimensional expansion of the acoustic model enables the system to provide consistent stereo perception for listeners at various positions around the speaker array

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

2Manufacturing precision

If beamforming wave field synthesis is used to generate virtual sources in front of the speaker array, then delays and gains are applied to create overlapping audio signals, but the stereo sensation is limited to specific listening positions

Engineering Contradiction:
Improvevirtual source positioning accuracyVSAvoidlistening position range
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The invention merges beamforming techniques with scattered wavefront synthesis. By combining the directed primary wavefronts (from beamforming) with omnidirectional secondary scattered wavefronts, the system achieves both precise virtual source positioning and extended listening position range, as the scattered components provide spatial redundancy

Inventive Principle:
Principle #5Merging (Combining)

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 solution provides a consistent stereo sound image and enhanced sense of presence for listeners regardless of their position, improving the stereo sensation and sense of envelopment by generating densely packed and delayed audio signals using primary and secondary wavefronts.

Implementation Method 1

a first delay computation unit configured to compute, based on rendering information about the multichannel speakers, a first delay corresponding to a primary wavefront which propagates in a predetermined traveling direction from a sound source

Methodology Applied
Scientific EffectWave propagation: Sound

Implementation Method 2

a second delay computation unit configured to compute, based on the rendering information about the multichannel speakers, a second delay corresponding to a secondary wavefront which is generated by the primary wavefront and has a scattering wavefront

Methodology Applied
Scientific EffectAcoustic scattering: Scattering

Data Source

PatentEP2770754B1Acoustic rendering device and acoustic rendering method
Publication Date: 2016.09.14 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA
  • EP2770754B1 patent drawingFigure 1A
  • EP2770754B1 patent drawingFigure 1B
  • EP2770754B1 patent drawingFigure 2

AI summary

An audio rendering device which uses multichannel speakers includes: a first delay computation unit (501) which computes, based on rendering information about the multichannel speakers, a first delay corresponding to a primary wavefront which propagates in a predetermined traveling direction from a sound source that is each of speakers included in the multichannel speakers; a second delay computation unit (502) which computes, based on the rendering information about the multichannel speakers, a second delay corresponding to a secondary wavefront which is generated by the primary wavefront and has a scattering wavefront; an addition unit (503) which adds up the first delay and the second delay to compute a total delay; and a delay filter (504) which applies the total delay to an input audio signal to generate a multichannel audio signal for use in rendering with the multichannel speakers, and outputs the multichannel audio signal to the multichannel speakers.