Flex-Connector Microphone Suspension for Hearing Device Vibration Isolation
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Solution Overview
Problem
Microphones in hearing devices are sensitive to mechanical vibrations due to rigid fixation, leading to increased sensitivity and reduced gain margin.
Innovation Solution
A flex connector is used to suspend the microphone, configured with a specific length to thickness ratio to lower the resonant frequency below the audible range, providing an electrical and mechanical connection while reducing vibration sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the microphone is rigidly fixed to the hearing device case, then the mechanical connection is strong and stable, but the microphone becomes highly sensitive to vibrations and the gain margin is reduced
Solution Approach 1:
A flex connector is introduced as an intermediary element between the microphone and the hearing device case. This flex connector provides a mechanical connection while simultaneously acting as a vibration isolator, allowing the microphone to be connected to the case without directly transmitting vibrations. The flex connector's compliant nature enables it to mediate between the need for mechanical stability and the need to reduce vibration sensitivity.
Solution Approach 2:
The flex connector is implemented as a flexible printed circuit board (FPCB) with specific dimensional ratios (length-to-thickness ratio of 10:1 to 100:1) that enable it to function as a vibration isolating film. The flexible nature of this thin film structure allows it to deform under vibration, thereby reducing the transmission of mechanical vibrations to the microphone while maintaining electrical connectivity.
2Reliability
If the flex connector has a high length to thickness ratio, then the resonant frequency is lowered below audible range, but the connector becomes more flexible and potentially less mechanically stable
Solution Approach 1:
The flex connector's dimensional parameters are specifically optimized with a length-to-thickness ratio between 10:1 and 100:1. This parameter change transforms the connector's mechanical properties, lowering its resonant frequency below the audible range (below 20 Hz) while maintaining sufficient mechanical stability for the application. The specific ratio range balances vibration isolation effectiveness with structural integrity.
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 suspension system reduces microphone sensitivity to vibrations above resonance, improving the gain margin and stability of hearing devices.
Implementation Method 1
the flex connector has a length to thickness ratio configured to lower a resonant frequency of the flex connector and the microphone below an audible range of interest
Data Source
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AI summary
Disclosed herein, among other things, are systems and methods for microphone suspension for mechanical feedback reduction in hearing devices. A hearing device includes a housing, hearing electronics within the housing, a microphone not connected to the housing, and a flex connector. The flex connector is configured to electrically and mechanically connect the microphone to the hearing electronics, and the flex connector has a length to thickness ratio configured to lower a resonant frequency of the flex connector and the microphone below an audible range of interest.