Hearing Aid Microphone Matching Using Receiver Feedback
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Solution Overview
Problem
Hearing aids with multiple microphones face challenges in maintaining directional performance due to variations in microphone production and over time, especially when the behind-the-ear and in-the-ear parts are replaced, leading to unmatched microphones.
Innovation Solution
A method for microphone matching in hearing aids that involves determining a reference microphone response difference and iteratively adapting the microphone gain using algorithms like LMS or NLMS to minimize the difference between microphone responses, allowing for improved matching without external processing devices or specialist services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If microphones are matched during production, then manufacturing precision is improved, but adaptability deteriorates when parts are replaced
Solution Approach 1:
The patent stores reference microphone response characteristics during an initial measurement phase (when microphones are known to be well-matched). This preliminary captured data serves as a baseline for later adaptive matching, allowing the system to recover original matching quality after part replacements without requiring re-measurement or external equipment.
Solution Approach 2:
The system continuously measures current microphone response characteristics and compares them against the stored reference characteristics. Based on the detected deviations, the system automatically adjusts microphone gains to minimize differences, creating a closed-loop feedback mechanism that maintains matching quality dynamically over time and across component replacements.
2Measurement precision
If external processing devices are used for microphone matching, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The hearing aid system performs microphone matching autonomously using its own internal resources - the receiver serves as a test signal source, and the existing signal processing chain is used for measurement and adjustment. This self-service approach eliminates the need for external processing devices, measurement equipment, or specialist intervention, thereby reducing system complexity while maintaining measurement precision.
Solution Approach 2:
The system uses the receiver (loudspeaker) for dual purposes: delivering audio output to the user and serving as a test signal source for microphone matching measurements. This multi-functionality eliminates the need for separate test equipment, reducing overall system complexity while enabling precise self-measurement of microphone characteristics.
3Manufacturing precision
If microphone matching is performed manually by specialists, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The system automatically performs microphone matching without requiring specialist intervention. The automated process uses the hearing aid's own components to generate test signals, measure microphone responses, calculate optimal gain adjustments, and apply corrections - all independently and without manual involvement, thereby dramatically improving productivity while maintaining matching precision.
Solution Approach 2:
The patent replaces manual mechanical adjustment processes (performed by specialists using physical equipment) with automated electronic signal processing and digital gain control. This substitution of electronic automation for manual mechanical procedures streamlines the matching process, enabling rapid execution without specialist involvement and significantly improving productivity.
Data Source
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AI summary
The invention relates to a method and an apparatus for performing a microphone matching of a hearing aid comprising a first microphone (310), a second microphone (320) and a receiver (420) in a predetermined spatial arrangement to each other. The method comprises the steps of: generating (110) an output sound signal by means of the receiver; picking up (120) a first and second input sound signal by the microphones while the output sound signal is generated; converting (130) the first and second input sound signals into electrical microphone output signals by means of the microphones; determining (140) a first and second microphone response of the microphones; determining (150) a microphone response difference (210) between the first and second microphone responses; determining (160) a matching difference (250) between the microphone response difference (210) and a predetermined reference microphone response difference (220); and adapting (170) at least a first microphone gain of the first microphone according to the matching difference to reduce the matching difference.