Localized Speaker Pairing With Phase Cancellation for Sound Leakage

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Solution Overview

Problem

Users find earphones or headphones uncomfortable and inconvenient for prolonged use, and existing methods like wave field synthesis with large-scale speaker arrays are impractical.

Innovation Solution

A speaker system that uses paired speaker units with opposite phase inputs to cancel sound outside a limited area, allowing sound to be heard only in the vicinity of the system, with additional features to control high-frequency sound leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If earphones or headphones are used for sound reproduction, then sound can be heard only by the user, but user comfort deteriorates due to pressure on ears and hairstyle disruption

Engineering Contradiction:
Improvesound leakage to surroundingsVSAvoiduser comfort
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent replaces the mechanical contact-based sound delivery system (earphones/headphones physically inserted into ears) with an acoustic field-based system (speaker units creating localized sound zones). This substitution eliminates the need for mechanical insertion while achieving the same sound isolation effect through acoustic phase cancellation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the acoustic parameters (phase and amplitude) of sound waves emitted by paired speaker units. By controlling the phase difference between adjacent speaker units, the system creates constructive interference in the user's ear direction and destructive interference in surrounding areas, achieving sound localization without physical contact.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If a large-scale speaker array is used for wave field synthesis, then sound can be reproduced in a controlled area, but device complexity increases significantly

Engineering Contradiction:
Improvesound leakage to surroundingsVSAvoidspeaker array scale
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent divides the sound reproduction task into multiple independent speaker units arranged in an array. Each speaker unit operates independently with controlled phase relationships, allowing the system to create localized sound zones without requiring a massive interconnected array. The segmentation enables modular deployment and simplified control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different acoustic characteristics (phase and amplitude) to different speaker units based on their positions in the array. Each speaker unit is configured to contribute to sound reinforcement in specific directional zones while creating cancellation in others, achieving localized sound control with a relatively simple array configuration.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If speaker units are used for sound reproduction, then user comfort is maintained, but sound reaches surroundings and becomes a nuisance to other users

Engineering Contradiction:
Improveuser comfortVSAvoidsound leakage to surroundings
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by emitting sound waves with opposite phase from adjacent speaker units before the sound can propagate to surrounding areas. This pre-emptive cancellation prevents harmful sound leakage rather than attempting to contain or block it after generation, achieving sound isolation through proactive acoustic interference.

Inventive Principle:
Principle #9Preliminary anti-action

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

Enables sound reproduction that is inaudible to others outside a small, defined area, enhancing user comfort and reducing sound leakage.

Implementation Method 1

paired speaker units with opposite phase inputs to cancel sound outside a limited area

Methodology Applied
Scientific EffectSound wave interference: Interference

Data Source

PatentEP4131990B1Loudspeaker system
Publication Date: 2026.03.11 NT T INC
  • EP4131990B1 patent drawingFigure 1
  • EP4131990B1 patent drawingFigure 2
  • EP4131990B1 patent drawingFigure 3

AI summary

A speaker system that reproduces sound inaudible to users around, without using earphones, headphones, or a large-scale speaker array, is provided. Assuming that N is an integer equal to or larger than one, and that a (2n - 1)-th sound signal (n = 1, ..., N) is a sound signal obtained based on a subject to be reproduced, a speaker system that emits sound based on a first sound signal, ..., and sound based on a (2N - 1)-th sound signal such that the sound is heard only in a vicinity, includes an n-th speaker unit pair (n = 1, ..., N) including a speaker unit that emits sound based on the (2n - 1)-th sound signal (hereinafter, referred to as the positive speaker unit) and a speaker unit that emits sound based on a 2n-th sound signal that is a sound signal with opposite phase to phase of the (2n - 1)-th sound signal (hereinafter, referred to as the negative speaker unit).