Hearing Device Feedback Suppression via Frequency-Selective Power Comparison
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Solution Overview
Problem
Existing hearing device systems face challenges in safely detecting and suppressing feedback-induced oscillations without reducing the overall functionality, particularly in binaural systems where ambient conditions and head shadowing effects complicate the differentiation between feedback and useful signals.
Innovation Solution
A method involving a frequency-selective power comparison of microphone signals from two spatially separated microphones, generating a quantitative signal indicating feedback, which is used to control adaptive compensation filters and suppress feedback, avoiding misinterpretation of tonal input signals as feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hearing device amplification is limited to suppress feedback-induced oscillations, then feedback is reduced, but the function of the hearing device system is reduced ad absurdum
Solution Approach 1:
The patent extracts the feedback component from the microphone signal using adaptive filters and compensation algorithms, separating it from the useful amplified signal. This allows selective suppression of feedback while preserving the hearing device's amplification function for useful sounds.
Solution Approach 2:
The patent implements a feedback suppression system that continuously monitors the microphone signal, detects feedback-induced oscillations, and dynamically adjusts compensation filters to neutralize the feedback component, creating a closed-loop control system that maintains amplification while suppressing feedback.
2Object-affected harmful factors
If notch filters are used to reduce loop amplification during adaptation, then feedback is suppressed in specific frequency ranges, but the characteristic of the feedback path cannot be reliably predicted under varying ambient conditions
Solution Approach 1:
The patent employs dynamic adaptation algorithms that continuously adjust the feedback suppression parameters based on real-time analysis of the feedback path characteristics. The system adapts to varying ambient conditions by monitoring changes in the feedback signal and adjusting the compensation filters accordingly, rather than relying on fixed notch filter frequencies.
Solution Approach 2:
The feedback suppression system automatically identifies and adapts to changing feedback path characteristics through continuous monitoring and analysis of the microphone signal. The system self-adjusts the compensation filters without requiring external calibration or prediction of feedback conditions.
3Productivity
If compensation algorithms with adaptive filters are used to estimate and neutralize feedback component, then hearing device amplification is preserved, but tonal input signals may be misinterpreted as feedback and incorrectly subtracted
Solution Approach 1:
The patent applies localized suppression by identifying specific frequency ranges where feedback occurs and applying compensation only in those narrow frequency bands, rather than broadly suppressing all signals. This preserves tonal input signals in other frequency ranges while targeting feedback-specific frequency components.
Solution Approach 2:
The system dynamically changes the parameters of the adaptive filters based on the detected characteristics of the feedback signal, adjusting filter coefficients, frequency ranges, and attenuation levels to match the specific feedback conditions while preserving useful tonal signals that differ in their spectral characteristics.
4Object-affected harmful factors
If oscillation detectors are used to monitor microphone signal and reduce amplification after detecting feedback, then feedback-induced oscillations are suppressed, but tonal narrowband input signals are also suppressed
Solution Approach 1:
The patent extracts the feedback component from the total microphone signal using spectral analysis and adaptive filtering, separating it from tonal input signals based on their different spectral characteristics. This allows selective suppression of feedback while preserving useful tonal signals.
Solution Approach 2:
The system dynamically adjusts the suppression level and frequency range based on the detected signal characteristics, applying stronger suppression to identified feedback components while maintaining amplification for tonal input signals that exhibit different temporal and spectral patterns.
Data Source
AI summary
There is described a method for operation of a hearing device system with two microphones arranged spatially separated from one another and with sound-generating output units assigned to these microphones, in which, by comparison of the microphone signals or of signals derived therefrom, feedback is detected, and on detection of the feedback measures are initiated for reducing the feedback, and with the comparison of the microphone signals or of signals derived therefrom comprising a frequency-selective power comparison. There is also described a hearing device system suitable for this method.