Acoustic Shield for Hearing Aid Test Coupler
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Solution Overview
Problem
Open fitting hearing aid measurements are not repeatable due to issues such as the summation of direct and processed sound causing a comb filter effect, sound leakage leading to acoustic feedback, and dependency on coupler orientation and processing delay in closed fitting conditions.
Innovation Solution
A system and method for open fitting hearing aid measurements using an acoustic shield with an ear simulator coupler and ear extension, which includes a sound-impervious acoustic shield with sound absorption material to minimize resonance and prevent sound leakage, allowing for accurate frequency response measurements without feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If open fitting hearing aid measurements are performed without acoustic shielding, then the measurements simulate INSITU conditions more closely, but the summation of direct and processed sound causes comb filter effect and acoustic feedback distorts the output signal
Solution Approach 1:
The measurement system is divided into separate functional zones: a test space for the hearing aid and sound source, and a shielded space for the ear simulator coupler. The acoustic shield physically segments the measurement path to prevent direct sound from reaching the coupler, eliminating the comb filter effect while maintaining open fitting simulation.
Solution Approach 2:
The acoustic shield acts as an intermediary element between the sound source and the ear simulator coupler. It allows processed sound to reach the coupler through the ear extension while blocking direct sound paths, thereby mediating the measurement to prevent acoustic feedback and comb filtering.
2Adaptability or versatility
If non-occluded coupler measurements are performed, then open fitting conditions are simulated, but sound leaking from the coupler leads to acoustic feedback that distorts the output signal
Solution Approach 1:
The acoustic shield creates separate acoustic zones that segment the feedback path. The shielded space isolates the coupler from direct sound exposure, preventing sound leakage from causing acoustic feedback while maintaining the open fitting configuration.
Solution Approach 2:
The system accepts that sound will leak from the open fit coupler but converts this potentially harmful effect into a beneficial measurement by using the acoustic shield to control the leakage path. The shield directs only the processed sound through the ear extension while blocking direct sound, turning leakage into a controlled measurement feature.
3Reliability
If closed fitting measurements are performed, then measurement repeatability is improved, but the frequency response deviates significantly from INSITU conditions
Solution Approach 1:
The acoustic shield provides localized acoustic control: the test space maintains open fitting conditions for natural sound processing, while the shielded space provides acoustic isolation for repeatable measurements. This local differentiation of acoustic properties allows both INSITU simulation and measurement reliability.
Solution Approach 2:
The measurement system segments the acoustic environment into an open test space and a shielded measurement space, allowing each zone to serve its specific function: simulating INSITU conditions where needed and ensuring measurement repeatability where required.
4Device complexity
If open fit measurements are performed without acoustic shielding, then the setup is simpler, but the summation and feedback effects make measurements non-repeatable and impractical
Solution Approach 1:
The acoustic shield divides the measurement system into distinct acoustic zones, creating a simple yet effective solution. The shielded space isolates the coupler from direct sound, eliminating complex feedback issues while maintaining overall system simplicity.
Solution Approach 2:
The acoustic shield serves as a simple intermediary structure that mediates between the sound source and coupler. This single added element resolves the repeatability issue without requiring complex active control systems or complicated measurement procedures.
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 solution provides repeatable and practical open fitting hearing aid measurements by eliminating the summation of direct and processed sound and reducing acoustic feedback, ensuring alignment and processing delay are no longer critical factors.
Implementation Method 1
sound-impervious acoustic shield with sound absorption material to minimize resonance and prevent sound leakage
Data Source
AI summary
In a system and method for open fitting hearing aid frequency response sound measurements, a test space is provided having located therein a sound source, a hearing aid with a microphone, and an open fit receiver. An acoustic shield is provided and within the acoustic shield an ear simulator coupler is provided having an ear extension attached thereto, the ear extension having mounted thereto at least a portion of the open fit receiver. A measurement unit receives sound signals from the ear simulator coupler.