Hearing Aid Feedback Canceler Adaptation via Tonality Detection
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Solution Overview
Problem
Adaptive feedback cancellation in hearing devices performs poorly with strongly self-correlated input signals like pitched speech and music, leading to entrainment artifacts that degrade sound quality and reduce stable gain.
Innovation Solution
A method that detects the strength of tonality in input signals by estimating the second derivative of subband phase and adjusts the parameters of the adaptive feedback canceler to mitigate entrainment, distinguishing tonal signals from feedback oscillations and adapting the feedback cancellation accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive feedback cancellation is used in hearing devices, then feedback suppression is improved, but sound quality deteriorates due to entrainment artifacts with tonal signals
Solution Approach 1:
The patent applies dynamics by making the feedback canceler adaptation dynamic and signal-dependent. The adaptation process is modulated based on the detected tonality of input signals, allowing the system to adapt when appropriate and freeze when tonal signals are present, thereby resolving the contradiction between feedback suppression and artifact generation
Solution Approach 2:
The patent changes the adaptation parameter (adaptation rate or freeze state) based on the tonality of the input signal. By detecting tonality and adjusting the adaptation parameter accordingly, the system prevents entrainment artifacts while maintaining feedback cancellation effectiveness, thus resolving the technical contradiction
2Reliability
If adaptive feedback canceler adapts continuously, then feedback cancellation performance is improved, but entrainment artifacts increase with tonal input signals
Solution Approach 1:
The patent introduces a feedback mechanism where the detected tonality of the input signal feeds back to control the adaptation process. This feedback loop allows the system to automatically adjust its adaptation behavior based on signal characteristics, preventing entrainment while maintaining cancellation performance
Solution Approach 2:
The adaptation process is made dynamic by freezing or slowing adaptation when tonal signals are detected and resuming normal adaptation when tonal signals are absent. This dynamic control resolves the contradiction by adapting the cancellation behavior to the instantaneous signal conditions
Data Source
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AI summary
Disclosed herein, among other things, are apparatus and methods for tonality-driven feedback canceler adaptation for hearing devices. Various embodiments include a method of signal processing an input signal in a hearing device to mitigate entrainment, the hearing device including a receiver and a microphone. The method includes detecting strength of tonality of the input signal by estimating a second derivative of subband phase of the input signal, and adjusting parameters of an adaptive feedback canceler of the hearing device based on the detected tonality.