Custom Earplug With Acoustic Waveguide for Mandibular Seal Consistency
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Solution Overview
Problem
Existing earplugs fail to maintain a consistent seal within the auditory canal due to mandibular movement, leading to gaps that allow loud sounds to propagate, and are prone to being fouled by cerumen or debris, compromising their noise attenuation performance.
Innovation Solution
A custom-molded earplug with a horn-shaped plug body and internal conduit that uses an elastic polymer and a closed membrane wall to create an acoustic waveguide, ensuring a consistent seal and attenuating specific sound frequencies through interference patterns and frequency filtering, while being resistant to debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous earplug materials are used to seal the auditory canal, then the ear canal can be sealed, but gaps appear around the material when the auditory canal shape changes due to mandibular movement
Solution Approach 1:
The earplug incorporates a resilient material that can dynamically adapt to shape changes in the auditory canal caused by mandibular movement. The material's elasticity allows it to maintain contact and seal integrity despite changes in canal geometry, resolving the contradiction between seal consistency and adaptability to shape changes.
2Manufacturing precision
If custom molded earplugs with fixed shape are used, then they can be engineered to attenuate certain frequency ranges, but the set shape is too resilient to adapt to continuous movement causing the earplug to loosen
Solution Approach 1:
The earplug uses material with specific elastic modulus and damping characteristics that allow it to maintain its engineered shape for frequency attenuation while simultaneously adapting to shape changes in the auditory canal. The material parameters are selected to balance structural integrity for acoustic filtering with flexibility for maintaining seal during mandibular movement.
3Manufacturing precision
If an internal sound attenuating filter is added to fix molded earplugs, then certain frequency ranges can be attenuated, but the earplug becomes difficult to insert into narrow ear canals
Solution Approach 1:
The acoustic filtering function is integrated directly into the earplug body structure rather than being a separate insertable component. The resonant frequency attenuation is achieved through the geometry and material properties of the earplug itself, eliminating the need for separate filters that would complicate insertion into narrow ear canals.
4Manufacturing precision
If an opening is provided in the earplug structure to face the eardrum, then sound can be attenuated, but the opening becomes blocked with cerumen compromising the attenuation level
Solution Approach 1:
The design eliminates openings that face the eardrum by using the earplug body itself to provide acoustic attenuation through resonant frequency filtering. The attenuation function is achieved through the closed-cell foam structure and geometric design of the earplug body, removing the vulnerability to cerumen blockage associated with open eardrum-facing ports.
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 earplug maintains effective noise attenuation across desired frequency ranges without compromising the seal, even with mandibular movement, and is less likely to be fouled by cerumen, ensuring reliable hearing protection.
Implementation Method 1
The internal conduit and the membrane wall both act upon incoming acoustic signals to both lower volume and attenuate certain undesired frequency ranges
Implementation Method 2
The internal conduit and the membrane wall both act upon incoming acoustic signals to both lower volume and attenuate certain undesired frequency ranges
Implementation Method 3
The plug body can be formed from an elastic polymer
Data Source
AI summary
An earplug device that is placed in the ear canal to attenuate sound frequencies within a selected frequency range. The earplug has a plug body with a first end, an opposite second end, and an exterior surface that extends from the first end to the second end. An opening is formed in the plug body at the first end. The opening leads to an internal conduit within the plug body. The internal conduit terminates at a closed membrane wall proximate the second end of the plug body. The internal conduit and the membrane wall both act upon incoming acoustic signals to both lower volume and attenuate certain undesired frequency ranges.