Adaptive Feedback Estimation Control for Hearing Aid Artefacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio processing devices, such as hearing aids, face challenges in minimizing the audibility of artefacts caused by acoustic feedback, especially in environments with tonal components like music, due to biased feedback path estimates from adaptive filters when the input signal is not white.
Innovation Solution
An audio processing device with a feedback estimation system that includes a de-correlation unit and an adaptive algorithm, where the control unit influences the de-correlation unit and adaptive algorithm based on auto-correlation and cross-correlation values to minimize artefact audibility, using a frequency shift and adjusting the adaptation rate to reduce feedback path errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive feedback cancellation is used to track feedback path changes over time, then system stability is improved, but artefact audibility increases when tonal components are present in the input signal
Solution Approach 1:
The patent applies dynamics by making the adaptation rate of the feedback estimation system controllable and variable over time. The system dynamically adjusts the adaptation rate based on detected tonal components in the input signal, allowing it to be higher when no tones are present (improving stability tracking) and lower when tones are detected (reducing artefact audibility).
Solution Approach 2:
The patent changes the adaptation rate parameter based on the presence of tonal components. When tones are detected in the input signal, the adaptation rate is reduced to minimize artefact generation. When no tones are present, the adaptation rate is increased to improve tracking of feedback path changes, thus resolving the contradiction between stability and artefact audibility.
2Speed
If the adaptation rate is increased to improve feedback path tracking, then system responsiveness is improved, but artefact generation increases in the presence of tonal components
Solution Approach 1:
The system dynamically changes the adaptation rate parameter based on tonal component detection. When tonal components are detected in the input signal, the adaptation rate is reduced to minimize artefact generation. When no tonal components are present, the adaptation rate is increased to improve feedback path tracking responsiveness.
Solution Approach 2:
The system uses feedback from tonal component detection to control the adaptation rate. The detection of tonal components provides feedback that triggers a reduction in adaptation rate, creating a closed-loop control system that adjusts parameters based on signal characteristics to minimize artefacts while maintaining tracking performance.
3Object-affected harmful factors
If open loop estimation is used to avoid bias from autocorrelation, then artefact audibility is reduced, but ability to track feedback path changes over time is lost
Solution Approach 1:
The patent implements a dynamic switching mechanism between open-loop and closed-loop estimation modes. When tonal components are detected, the system switches to or maintains open-loop estimation to avoid artefacts. When no tonal components are present, it uses closed-loop adaptive estimation to track feedback path changes, thus resolving the contradiction between avoiding artefacts and maintaining tracking capability.
Data Source
AI summary
An audio processing device comprises a feedback estimation system for estimating feedback from an output transducer to an input transducer, the feedback estimation system comprising an adaptive filter comprising a variable filter part for filtering an input signal according to variable filter coefficients and an algorithm part comprising an adaptive algorithm for dynamically updating filter coefficients, a control unit for controlling the de-correlation unit and the adaptive algorithm, and a correlation detection unit for determining a) the auto-correlation of a signal of the forward path and providing an AC-value and/or b) the cross-correlation between two different signals of the forward path and providing an XC-value.