Double Hearing Protection Tether Seal Integrity
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Solution Overview
Problem
Current hearing protection devices fail to provide maximum noise attenuation in high ambient noise environments while preventing foreign object damage (FOD) and maintaining performance, as existing solutions either compromise on noise reduction or introduce FOD risks due to tethered earplugs.
Innovation Solution
A double hearing protection device featuring a circumaural hearing protector with a non-rigid tether connecting the earplug, retracting into the earcup to prevent seal breakage and snag hazards, allowing manual earplug placement and easy access without removing the headset, and incorporating a coiled multi-conductor cable for active noise reduction and communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-tethered foam earplug is used under a circumaural hearing protector, then maximum noise attenuation is achieved, but the risk of foreign object damage (FOD) increases as the earplug may become separated and be ingested into aircraft engines
Solution Approach 1:
A tether assembly acts as an intermediary component connecting the earplug to the circumaural hearing protector. The tether includes a first portion attached to the earplug and a second portion attached to the interior of the earcup, creating a mechanical link that prevents the earplug from becoming detached while allowing it to remain positioned in the ear canal for effective noise attenuation.
2Object-affected harmful factors
If a tether is attached to connect the earplug to the circumaural hearing protector, then foreign object damage is prevented, but the seal between the earcup and the head may be broken, degrading noise attenuation performance
Solution Approach 1:
The tether is segmented into multiple portions: a first portion extending from the earplug, a second portion attached to the interior of the earcup, and optionally a third portion connecting the first and second portions. This segmentation allows the tether to be routed through the ear canal space without necessarily contacting or breaking the seal between the earcup and the user's head, thereby maintaining both FOD prevention and noise attenuation performance.
Solution Approach 2:
The tether is positioned and routed in the third dimension within the ear canal and earcup interior space. By utilizing the vertical and radial dimensions within the ear canal, the tether can connect the earplug to the earcup structure without interfering with the horizontal seal interface between the earcup and the user's head, thus preventing FOD while maintaining seal integrity.
3Object-affected harmful factors
If a rigid tether is used to connect the earplug, then FOD prevention is achieved, but structural vibration paths are created that degrade hearing protection performance
Solution Approach 1:
The tether is constructed from flexible materials rather than rigid structures. This flexibility allows the tether to prevent FOD by maintaining connection between the earplug and earcup, while simultaneously dampening structural vibrations and avoiding the creation of rigid vibration paths that would transmit noise directly to the earplug, thereby preserving hearing protection performance.
4Ease of operation
If the entire circumaural hearing protector assembly is removed to access the earplug, then earplug replacement is possible, but the complexity of donning and doffing increases and time is lost
Solution Approach 1:
The circumaural hearing protector assembly is segmented to allow independent access to the earplug. The earcup can be opened or adjusted without removing the entire headband and circumaural structure, enabling users to replace earplugs quickly by simply opening the earcup while the headband remains in place on the user's head.
Solution Approach 2:
The design enables self-service earplug replacement where the user can independently access and replace the earplug without requiring assistance or removal of the main hearing protector structure. The tethered connection ensures the earplug remains attached to the system throughout this process, allowing for quick swaps without losing the earplug or requiring complete disassembly.
Data Source
AI summary
A double hearing protection system comprises a circumaural hearing protector that covers and encircles the pinnae and an earplug device that is inserted into the ear canal. The earplug portion of the system comprises a tether that is coupled to the interior of a circumaural hearing protector. The tether retracts into the earcup when both the earplug and circumaural hearing protector are worn, ensuring that the earseal against the head is not broken by the retractable tether.