Damped Earplug Elastomer for High Sound Attenuation

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Solution Overview

Problem

Existing push-in type earplugs provide lower sound attenuation compared to roll-down types, while being easier to insert and having a longer usage lifetime, but attempts to increase their NRR have resulted in reduced comfort and only moderate improvements.

Innovation Solution

A push-in type earplug composed of a highly damped elastomer material with an increased glass transition temperature and reduced glass-to-rubber transition temperature, providing enhanced sound attenuation over a range of temperatures and frequencies, combined with a rigid stem portion for easy insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If push-in type earplugs are made with traditional soft conformable material, then ease of insertion is improved, but sound attenuation is reduced

Engineering Contradiction:

Improveease of insertionVSAvoidsound attenuation

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by modifying the material's glass transition temperature and glass-to-rubber transition temperature to optimize damping characteristics. The elastomer is formulated with specific transition temperatures that maximize damping factor in the range of -20°C to 50°C, thereby improving sound attenuation without compromising the soft conformable properties needed for easy insertion.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining elastomer with specific additives and plasticizers to create a multi-component system. The composite formulation includes base elastomer, plasticizers, and other compounds working together to achieve both the desired softness for insertion and enhanced damping properties for sound attenuation.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If roll-down type earplugs are used to achieve higher sound attenuation, then noise reduction rating is improved, but ease of insertion and usage lifetime are reduced

Engineering Contradiction:

Improvesound attenuationVSAvoidease of insertion

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent changes the material parameters by adjusting the glass transition temperature and glass-to-rubber transition temperature of the elastomer. This creates a material with optimized damping characteristics that achieves higher sound attenuation comparable to roll-down plugs, while maintaining the push-in format for easier insertion and longer usage lifetime.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If attempts are made to increase NRR of push-in earplugs with traditional materials, then sound attenuation is improved, but comfort is reduced

Engineering Contradiction:

Improvesound attenuationVSAvoidcomfort

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent optimizes material parameters by carefully controlling the glass transition temperature and glass-to-rubber transition temperature to maximize damping factor while maintaining material softness. This parameter optimization achieves higher NRR without compromising comfort, as the material remains soft and conformable despite enhanced damping properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials with specific elastomer formulations including plasticizers and additives that work together to provide both high damping factor for sound attenuation and softness for comfort. The composite structure allows simultaneous achievement of high NRR and user comfort.

Inventive Principle:

Principle #40Composite materials

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 damped earplug achieves increased sound attenuation, resulting in a projected 3 dB higher Noise Reduction Rating (NRR) with improved comfort and longer usage lifetime, while maintaining ease of use.

Implementation Method 1

hearing protection devices composed at least partially of a damped material for providing enhanced sound attenuation

Methodology Applied

Scientific EffectDamping: Damping

Implementation Method 2

The sound attenuating portion is typically formed of a soft conformable material

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

an elastomer with an increased glass transition temperature and a reduced glass-to-rubber transition temperature

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 4

the damping factor of the material peaks at a higher temperature

Methodology Applied

Scientific EffectPhase Change: Phase Change

Data Source

PatentUS8118031B2Hearing protection device with damped material

Publication Date: 2012.02.21 3M INNOVATIVE PROPERTIES CO

AI summary

The invention provides a hearing protection device having an attenuating body composed of an elastomer with an increased glass transition temperature and a reduced glass-to-rubber transition temperature such that the damping factor of the material peaks at a higher temperature and, resultantly, the damping factor is increased over a range of temperatures and frequencies typically experienced by the device during usage. The increased damping results in higher sound attenuation provided by the hearing protection device.