Adaptive Microphone Matching for Hearing Systems
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Solution Overview
Problem
Existing hearing systems face challenges in achieving satisfactory beamforming performance due to insufficient phase matching of microphones, particularly at low frequencies, leading to group delay differences of up to 80µs, which is beyond the desired 10µs limit for effective beamforming.
Innovation Solution
An adaptive method that determines a true direction towards a sound source by limiting a frequency range where microphones are well matched, calculates a correction factor by comparing this direction with an estimated direction, and applies this factor to the microphone signals to reduce phase differences, thereby improving beamformer performance, especially at low frequencies, without requiring static calibration methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard microphone matching procedures or models are used, then the beamformer algorithm can be improved to some extent, but the matching precision remains insufficient due to wrong assumptions or insufficient models
Solution Approach 1:
The patent implements an adaptive feedback mechanism where the system continuously monitors the actual performance of the beamformer and adjusts the microphone matching parameters in real-time. The controller receives feedback about the beamforming effectiveness and automatically modifies the matching parameters to optimize performance, eliminating the need for precise pre-established models or assumptions about error situations.
Solution Approach 2:
The patent transitions from static microphone matching (using fixed models or procedures) to dynamic adaptive matching. The matching parameters are not fixed but continuously adjusted based on actual operating conditions and performance feedback, allowing the system to adapt to varying acoustic environments and microphone characteristics.
2Device complexity
If microphones are used without additional matching methods, then the device complexity is reduced, but the beamforming performance at low frequencies becomes unsatisfactory due to group delay differences up to 80µs
Solution Approach 1:
The patent enables the hearing system to perform self-adjustment of microphone matching parameters. The system automatically measures its own beamforming performance and adjusts the matching parameters without requiring external calibration equipment or complex pre-matching procedures, thereby maintaining simplicity while achieving precise low-frequency beamforming.
Solution Approach 2:
The patent dynamically changes the microphone matching parameters (such as phase and gain adjustments) based on measured performance metrics. By continuously adjusting these parameters rather than using fixed values, the system achieves precise beamforming at low frequencies without requiring complex hardware modifications or additional matching components.
3Measurement precision
If static calibration methods are used to match microphones, then the initial matching can be improved, but the system lacks adaptability to changing conditions and requires additional calibration time
Solution Approach 1:
The patent implements continuous feedback-based adaptation that allows the system to maintain optimal microphone matching under varying acoustic conditions. The system monitors beamforming performance in real-time and automatically adjusts matching parameters, providing both high precision and adaptability without requiring repeated static calibration procedures.
Solution Approach 2:
The patent transforms the static calibration approach into a dynamic adaptive system. Instead of performing fixed calibration procedures during production or fitting, the system continuously adapts the microphone matching parameters based on real-time performance feedback, ensuring both precision and adaptability to changing environmental conditions.
Data Source
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AI summary
A method and a hearing system for adaptively matching microphones (3, 4) of a hearing system are disclosed. The method comprising the steps of determining a true direction towards a sound source, determining an estimated direction towards the sound source using microphones (3, 4) of the hearing system, comparing the true direction with the estimated direction to obtain a correction factor, applying the correction factor to the signals of the microphones (3, 4) of the hearing system in order to reduce a difference between the true direction and a corrected estimated direction obtained via corrected microphone signals.