Headrest Speaker Sound Localization with Front-Speaker Panning

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Solution Overview

Problem

Existing sound localization techniques using headrest speakers in vehicles fail to enhance the sense of presence for listeners, as they primarily focus on localizing virtual sound images on the front side of the head, neglecting the potential of front speakers for supplementary sound supplementation.

Innovation Solution

A sound processing device that utilizes both headrest and front speakers to achieve a two-step sound image localization process, where a tentative sound image is first localized by headrest speakers in a region excluding the front side and then supplemented by amplitude panning to finalize the sound image between the headrest and front speakers, enhancing the sense of presence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If only headrest speakers are used for sound localization, then the system complexity is reduced, but the sense of presence is insufficient

Engineering Contradiction:
Improvesense of presenceVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines headrest speakers and front speakers into a unified sound localization system. The headrest speakers create a tentative sound image in the rear hemisphere, while front speakers supplement this image to enhance the sense of presence, achieving improved auditory realism through merged speaker functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sound localization process is segmented into two distinct stages: first, headrest speakers localize a tentative sound image in the rear hemisphere; second, front speakers supplement this image. This segmentation allows each speaker type to perform its optimal function while contributing to the overall sense of presence.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If sound images are localized only on the front side of the head, then the localization region is simplified, but the immersive listening experience is reduced

Engineering Contradiction:
Improvelocalization region coverageVSAvoidprocessing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extends sound localization from the traditional front-side region to include the rear hemisphere by utilizing headrest speakers. This dimensional expansion creates tentative sound images in previously unused spatial regions, thereby expanding the overall localization region coverage and enhancing immersion.

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

3Reliability

If a two-step localization process is implemented, then the sense of presence is improved, but the processing time increases

Engineering Contradiction:
Improvesense of presenceVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The headrest speakers first create a tentative sound image in the rear hemisphere as a preliminary step. This preliminary localization provides a spatial foundation that the front speakers then supplement, allowing the two-step process to occur rapidly and sequentially rather than requiring complex simultaneous processing.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4412246B1Sound processing device, sound system, and sound processing method
Publication Date: 2025.10.22 ALPS ALPINE CO LTD
  • EP4412246B1 patent drawingFigure 1
  • EP4412246B1 patent drawingFigure 2
  • EP4412246B1 patent drawingFigure 3

AI summary

The sound processing device includes the first processor that performs the trans-aural process on the signals corresponding to the plurality of headrest speakers so that a tentative sound image is localized by the plurality of headrest speakers at a tentative position within a region which does not include the front side of the head but includes the left and right sides and the back side of the head, and the second processor that performs the amplitude panning on signals corresponding to the front speakers and a signal processed by the first processor so that a final sound image is localized at a final position between a tentative sound image and the front speakers in accordance with a difference in volume between the tentative sound image and the front speakers.