Hearing Aid Online Anti-feedback System
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Solution Overview
Problem
Hearing aids often become unstable and produce howls when the loop gain exceeds 1, and existing feedback compensation methods either require external adjustments or are not adaptive enough to handle varying acoustical environments.
Innovation Solution
An online anti-feedback system that continuously estimates the feedback path and adjusts the maximum allowable gain in the hearing aid's forward path, using an adaptive filter to minimize acoustical feedback and prevent howls by dividing the frequency range into bands and dynamically updating gain values based on current feedback conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the loop gain is increased to provide more amplification for hearing impaired users, then the hearing aid gain is improved, but the system becomes unstable and produces howls when loop gain exceeds 1
Solution Approach 1:
The patent implements a feedback cancellation system that continuously monitors the acoustic feedback path from the receiver to the microphone and generates an anti-feedback signal to cancel the howling. The system uses an adaptive filter to model the feedback path and subtracts the estimated feedback from the microphone signal, allowing the hearing aid to operate at higher gains without instability.
Solution Approach 2:
The patent dynamically adjusts the maximum allowable gain based on the estimated feedback path characteristics. By continuously updating the feedback model and calculating the maximum stable gain, the system can adaptively change the gain parameter to prevent howls while maximizing amplification for the hearing impaired user.
2Reliability
If a traditional feedback cancellation system is used, then howls are suppressed, but the system requires external equipment and manual adjustments by technicians
Solution Approach 1:
The patent implements an automated feedback management system that performs feedback path estimation and maximum gain calculation without requiring external equipment or technician intervention. The hearing aid autonomously adapts to changing acoustic environments and adjusts its gain settings, eliminating the need for manual feedback management while maintaining effective howl suppression.
3Device complexity
If the hearing aid uses a fixed gain setting, then the system is simple to implement, but it cannot adapt to varying acoustical environments and feedback conditions
Solution Approach 1:
The patent implements a dynamic feedback management system that continuously estimates the feedback path using an adaptive filter and adjusts the maximum allowable gain in real-time based on changing acoustic conditions. The system transitions from static gain settings to dynamic adaptation, allowing the hearing aid to maintain optimal performance across varying environments while managing feedback automatically.
Data Source
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AI summary
A hearing aid system comprises an input transducer, a forward path, an output transducer and an electrical feedback path, the forward path comprising a signal processing unit for modifying an electrical input signal to a specific hearing profile over a predefined frequency range, wherein the predefined frequency range comprises a number of frequency bands, for which maximum forward gain values IGmax for each band are stored in a memory. The electrical feedback path comprises an adaptive filter for estimating acoustical feedback from the output to the input transducer. The hearing aid system further comprises an online feedback manager unit for - with a predefined update frequency - identifying current feedback gain in each frequency band of the feedback path, and for subsequently adapting the maximum forward gain values IGmax in each of the frequency bands in dependence thereof in accordance with a predefined scheme, and wherein the update frequency is adapted to a relevant hearing situation. The invention may e.g. be used in digital hearing aids for use in a variety of acoustical environments.