Adaptive Division Frequency for Hearing Aid Feedback Suppression
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Solution Overview
Problem
Hearing aid devices face challenges in effectively suppressing acoustic feedback due to the close proximity of microphone and output transducers, leading to unpleasant howling sounds, and existing methods often result in disruptive artefacts from superimposed signal components.
Innovation Solution
A method that divides the acoustic frequency range into two parts, estimates the feedback loop transfer function in the first frequency range, and adjusts the division frequency to prevent feedback loop gain from exceeding a predetermined limit, applying phase or frequency shifts only in the necessary frequency range to minimize artefacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback suppression is applied across the entire frequency range, then feedback suppression effectiveness is improved, but disruptive artefacts increase due to superimposition of phase-shifted and unchanged signal components
Solution Approach 1:
The frequency range is divided into a first frequency range (above division frequency) where feedback suppression with phase shift is applied, and a second frequency range (below division frequency) where no feedback suppression is applied. This segmentation prevents superimposition of phase-shifted and unchanged signal components, eliminating disruptive artefacts while maintaining feedback suppression effectiveness in the critical higher frequency range.
Solution Approach 2:
Feedback suppression with phase shifting is applied locally only in the first frequency range above the division frequency, rather than uniformly across all frequencies. This local application targets the frequency range most prone to feedback while avoiding artefact generation in lower frequencies where such suppression is less critical.
2Reliability
If phase shift or frequency shift is applied to improve feedback suppression, then feedback suppression is improved, but signal components superimpose and create disruptive artefacts
Solution Approach 1:
The frequency spectrum is segmented into two distinct ranges separated by a division frequency. Phase shift or frequency shift is applied exclusively to signal components in the first frequency range (above division frequency), while components in the second frequency range (below division frequency) remain unchanged. This segmentation eliminates the superimposition of phase-shifted and unchanged components that causes disruptive artefacts.
3Measurement precision
If transfer function estimation is performed in all frequency ranges, then measurement precision is improved, but computational resources are wasted in frequency ranges not prone to feedback
Solution Approach 1:
Transfer function estimation is performed locally only in the first frequency range (above division frequency) where feedback is most likely to occur and where phase shifting is applied for feedback suppression. This localized estimation concentrates computational resources on the critical frequency range, improving efficiency without sacrificing feedback suppression performance.
Solution Approach 2:
Instead of performing complete transfer function estimation across the entire frequency spectrum, the method performs partial estimation only in the higher frequency range above the division frequency. This partial action is sufficient to achieve effective feedback suppression in the critical frequency range while significantly reducing computational resource consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the occurrence of disruptive artefacts and ensures that feedback suppression is adapted to the specific acoustic environment, conserving resources by estimating the transfer function only in frequency ranges prone to feedback, thereby enhancing the overall feedback suppression in hearing aid devices.
Implementation Method 1
applying phase or frequency shifts only in the necessary frequency range to minimize artefacts
Implementation Method 2
applying phase or frequency shifts only in the necessary frequency range to minimize artefacts
Implementation Method 3
A method that divides the acoustic frequency range into two parts, estimates the feedback loop transfer function in the first frequency range
Implementation Method 4
estimates the feedback loop transfer function in the first frequency range
Data Source
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AI summary
The invention relates to a method for suppressing acoustic feedback in a hearing aid, as well as a corresponding device and system. In the method, a frequency range to be transmitted by the hearing aid is divided into two frequency ranges separated by a division frequency. A transfer function of a feedback path is estimated in one frequency range and its behavior at the division frequency is evaluated. Depending on the result of the evaluation, the division frequency is lowered or raised, and a phase and/or frequency change is applied in the upper frequency range to suppress feedback.