Hearing Aid Microphone Vibration Isolation
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Solution Overview
Problem
Hearing aids face imperfections due to microphone sensitivity to vibrations, leading to unwanted sound feedback and limitations in gain application, as existing solutions require complex microphone constructions or multiple diaphragms for vibration cancellation.
Innovation Solution
The proposed solution involves a microphone unit and inlet element arrangement within a hearing aid housing, where the microphone unit and inlet element are oriented such that their pressure build-ups are of equal but opposite signs, canceling out vibrations without the need for additional signal processing, using a single microphone with a larger back volume for enhanced sensitivity and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a receiver is placed in close proximity to a microphone in a hearing aid, then the device can be made more compact, but vibrations from the receiver will be transmitted to the microphone causing unwanted sound feedback and reducing reliability
Solution Approach 1:
A vibration isolation element is introduced as an intermediary component between the receiver and the microphone housing. This element acts as a mechanical mediator that blocks vibration transmission while allowing the receiver to remain in close proximity to the microphone, thus maintaining compact device size while improving microphone performance stability.
2Measurement precision
If the sensitivity of the microphone to vibrations is increased to improve sound detection, then the microphone can detect weaker sounds better, but it will also amplify unwanted vibration signals from the receiver and environment
Solution Approach 1:
The vibration isolation element converts the harmful effect of vibrations into a beneficial filtering mechanism. It allows the microphone to maintain high sensitivity for detecting weak sound signals while selectively blocking harmful vibration frequencies from the receiver and environment, thus transforming vibration sensitivity from a disadvantage into a controlled feature.
3Reliability
If a complex microphone construction with multiple diaphragms is used to cancel vibrations, then vibration cancellation performance is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The vibration isolation function is extracted from the microphone construction itself and placed in a separate vibration isolation element between the receiver and microphone housing. This extraction allows the microphone to maintain a simple single-diaphragm construction while still achieving effective vibration cancellation through the dedicated isolation component.
4Power
If gain is increased to compensate for ear structure amplification, then the hearing aid can provide better hearing assistance, but it will also unintentionally enhance unwanted vibration signals
Solution Approach 1:
Vibration isolation is implemented as a preliminary action before the sound signals reach the microphone and before amplification is applied. By blocking vibration transmission at the source (between receiver and microphone), the system prevents unwanted vibration signals from entering the amplification chain, allowing high gain to be applied safely without enhancing harmful signals.
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
This arrangement effectively cancels out microphone vibration sensitivity, improving signal-to-noise ratio and low-frequency response, while maintaining a simple construction that does not require a two-microphone setup, thus reducing unwanted sound feedback and enhancing sound reproduction.
Implementation Method 1
a movable element separates the first and second chamber... contributions from the microphone unit and the microphone inlet element, respectively, to a vibration sensitivity of the microphone... are substantially equal but of opposite sign
Data Source
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AI summary
An electronic device, such as a hearing aid. The electronic device comprising a microphone unit, which are arranged in a hearing aid housing so as to optimize the vibration sensitivity of the microphone unit towards changes in the environment, potentially causing the housing to be influenced by vibrations, is disclosed. Furthermore, a method of arranging a microphone unit in an electronic device is disclosed.