Ear Cushion Acoustic Impedance Zoning for Gap Noise Reduction

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Solution Overview

Problem

Conventional listening devices, such as earphones, fail to effectively prevent environmental noise from leaking into the ear canal due to gaps formed by objects like glasses or face masks, compromising passive noise reduction.

Innovation Solution

An annular ear cushion with a foam core and a cover having varying acoustic impedances, including a portion with a lower impedance to divert sound through the foam core and dissipate it, and another portion with higher impedance to reflect sound, minimizing noise entry through gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional ear cushions with uniform high acoustic impedance cover are used, then sound reflection is effective, but sound leaks through gaps formed by glasses or face masks

Engineering Contradiction:

Improveenvironmental noiseVSAvoidnoise reduction performance

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The cover is divided into different regions with different acoustic impedance characteristics: a first region with high acoustic impedance for sound reflection and a second region with low acoustic impedance for sound absorption. This local differentiation allows the ear cushion to handle both reflected and leaked sound effectively, resolving the contradiction between maintaining noise reduction performance and adapting to gap conditions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The ear cushion combines multiple materials with different acoustic properties: a foam core material and a cover material with varying acoustic impedances. This composite structure enables the cushion to simultaneously reflect sound through high-impedance regions and absorb leaked sound through low-impedance regions, effectively addressing the technical contradiction.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If the cover has high acoustic impedance to reflect sound, then passive noise reduction is effective, but sound energy accumulates and may cause discomfort

Engineering Contradiction:

Improveenvironmental noiseVSAvoidsound pressure

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The cover incorporates a second region with low acoustic impedance specifically designed to absorb sound energy that leaks through gaps. This local absorption capability prevents sound energy accumulation and reduces sound pressure in gap areas, while the first region continues to provide sound reflection for overall noise reduction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The low acoustic impedance region converts the harmful effect of sound leakage into a beneficial sound absorption mechanism. Instead of allowing sound to directly enter the ear canal through gaps, the design guides leaked sound into the absorption region where it is dissipated, transforming the potential harm into a protective feature.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 ear cushion effectively reduces environmental noise by reflecting and dissipating sound, maintaining passive noise reduction even when gaps form between the cushion and the user's head.

Implementation Method 1

the first portion of the cover has a second acoustic impedance that is greater than the first acoustic impedance... the second acoustic impedance may be at least five or ten times greater than the first acoustic impedance

Methodology Applied

Scientific EffectAcoustic impedance mismatch: Reflection

Implementation Method 2

at least one first subportion of the second portion of the cover has a third acoustic impedance that is smaller than the second acoustic impedance... the foam core having a first acoustic impedance

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentUS12495236B2Ear cushion, an earphone and a binaural listening device

Publication Date: 2025.12.09 GN HEARING AS

AI summary

Disclosed is an annular ear cushion for an earphone configured to be worn at an ear of a user. The ear cushion is configured to abut the head of the user along an annular contact surface of the ear cushion and to abut or face a housing of the earphone along an annular attachment surface of the ear cushion when the user is wearing the earphone in its intended position, thereby reducing the level of sound entering the ear canal of the user from the environment. The ear cushion further comprising an annular exterior surface and an annular interior surface each extending from the contact surface to the attachment surface and facing respectively the environment and the ear canal of the user when the user is wearing the earphone in its intended position. The ear cushion further comprising a foam core (150) having a first acoustic impedance, and a cover having a first portion extending across the exterior surface and a second portion extending across the contact surface. The first portion of the cover has a second acoustic impedance that is greater than the first acoustic impedance, wherein that at least one first subportion of the second portion of the cover has a third acoustic impedance that is smaller than the second acoustic impedance.