Microphone Matching Using Dual-Loop Amplitude and Phase Compensation
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Solution Overview
Problem
Existing microphone matching systems in hearing aids, such as those described in European patent applications EP 1 458 216 and EP 0 982 971, are inadequate as they only provide single-loop adjustments, leading to insufficient matching of microphones, and amplitude compensation is not directly referenced to the reference microphone, resulting in suboptimal directional focus in noisy environments.
Innovation Solution
A dual-loop system that includes amplitude and phase compensation using a phase matching unit with controllable low-pass and high-pass filters, and a comparator to adjust filter cut frequencies based on signal energy comparisons, ensuring precise matching of microphones by continuously monitoring and compensating for zero and pole variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-loop adjustment system is used for microphone matching, then the system complexity is reduced, but the matching precision of microphones is insufficient
Solution Approach 1:
The patent divides the microphone matching system into two independent adjustment loops: a first adjustment loop for adjusting poles and a second adjustment loop for adjusting zeros. Each loop independently processes and adjusts specific characteristics of the microphone signals, allowing for more precise matching without requiring a single complex system. This segmentation enables better matching precision while keeping each individual loop relatively simple.
2Ease of operation
If amplitude compensation is executed independently without direct reference to the reference microphone, then the system operation is simplified, but the matching reliability is reduced
Solution Approach 1:
The patent implements feedback mechanisms in both adjustment loops. The first adjustment loop uses feedback to continuously monitor and adjust pole characteristics by comparing the first microphone signal with the reference microphone signal. Similarly, the second adjustment loop uses feedback to adjust zero characteristics. This feedback ensures that amplitude compensation is directly referenced to the reference microphone, improving matching reliability while maintaining operational simplicity through automated closed-loop control.
Data Source
AI summary
This invention relates to a system (10) and method for matching one or more microphones. A first and second microphone (110, 210) communicates, respectively, a first and second microphone signal to an amplitude compensating means (16) adjusting amplitude of the first microphone signal in accordance with amplitude of the second microphone signal. The amplitude compensating means (16) communicates an adjusted first microphone signal (100) and the second microphone signal (200) to a phase matching means (18) comprising a correction filter means (113) receiving the adjusted first microphone signal (100). The correction filter means (113) comprises a low-pass filter means (111), which is controlled in accordance with a subtraction between the first microphone signal output (102) and the second microphone signal (200), and a high-pass filter means (112), which is controlled in accordance with a comparison between the first microphone signal output (102) and the second microphone signal (200).