Hearing Device Feedback Elimination via Frequency Synthesis
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Solution Overview
Problem
Existing hearing devices face challenges in completely eliminating acoustic feedback and noise without introducing audible distortions, as current feedback cancellation techniques often distort the audio signal and fail to accurately estimate dynamic feedback, while noise reduction methods can attenuate speech signals.
Innovation Solution
A system and method that synthesizes selected frequency bands of an incoming audio signal, allowing for the removal of acoustic feedback and noise by filtering out specific frequency bands and reconstructing the original signal, using a combination of filter units, synthesizer units, and amplifier units to ensure accurate sound restoration without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback cancellation techniques are used to eliminate acoustic feedback, then feedback elimination is improved, but audible distortions are introduced in the audio signal
Solution Approach 1:
The patent extracts and removes only the feedback component from the audio signal using a feedback indicator parameter signal, while preserving the original audio signal. The feedback-inhibiting filter is controlled to target specifically the feedback frequencies, allowing complete feedback elimination without removing useful audio content, thus avoiding audible distortions.
Solution Approach 2:
The patent uses a feedback mechanism where a probe signal is fed back through the acoustic feedback path to detect feedback levels. The feedback indicator parameter signal is generated based on this feedback detection and used to control the feedback-inhibiting filter, creating a closed-loop system that adapts to changing feedback conditions while maintaining audio quality.
2Reliability
If feedback cancellation techniques are used to eliminate acoustic feedback, then feedback elimination is improved, but accuracy of feedback estimation deteriorates
Solution Approach 1:
The patent introduces a probe signal as an intermediary to accurately measure the acoustic feedback path. This probe signal is separate from the main audio signal and is used to generate the feedback indicator parameter signal. By using this intermediary probe signal, the system can accurately estimate feedback characteristics without being affected by the complexity of the original audio signal, improving estimation accuracy.
3Object-affected harmful factors
If noise reduction techniques are used to reduce external noise, then noise reduction is improved, but speech signals are attenuated
Solution Approach 1:
The patent applies local quality by targeting specific frequency bands for feedback elimination rather than applying broad-spectrum filtering. The feedback-inhibiting filter is controlled to remove only the feedback component at specific frequencies, while other frequency bands containing speech information remain unaffected. This localized approach reduces noise and feedback without attenuating useful speech signals.
Data Source
AI summary
This invention relates to a system (100) and method for synthesizing an audio input signal of a hearing device. The system (100) comprises a microphone unit (102) for converting the audio input signal to an electric signal, a filter unit (110) for removing a selected frequency band of the electric signal and pass a filtered signal, a synthesizer unit (118) for synthesizing the selected frequency band of the electric signal based on the filtered signal thereby generating a synthesized signal, a combiner unit (120) for combining the filtered signal and the synthesized signal so as to generate a combined signal, and finally an output unit (122, 124, 126) for converting the combined signal to an audio output signal.