Hearing Aid Adaptive Feedback Compensation via Synthesized Signal
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Solution Overview
Problem
Existing hearing aids face challenges in reducing bias in adaptive feedback cancellation, particularly due to correlated input signals like music, which affect the accuracy of feedback suppression, especially in frequency regions above 2 kHz.
Innovation Solution
A hearing aid design incorporating a synthesizer that generates a synthesized signal based on a sound model, which is not correlated with the input signal, and includes this signal in the audio output to reduce bias, using linear prediction analysis and coding, and noise generators to simplify circuitry and improve feedback compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive feedback cancellation is used to suppress feedback, then feedback suppression is improved, but bias is introduced due to correlated input signals such as music
Solution Approach 1:
A synthesizer is introduced as an intermediary component that generates a synthesized signal based on a sound model. This synthesized signal is added to the audio output signal to act as a mediator that reduces the correlation between input and output signals, thereby reducing bias in the adaptive feedback cancellation algorithm while maintaining feedback suppression effectiveness
Solution Approach 2:
The patent changes the statistical parameters of the output signal by introducing a synthesized signal with different correlation characteristics. The synthesized signal has been designed to have low correlation with the input signal, which changes the joint statistical properties of the signal pair and reduces the bias in feedback path estimation caused by correlated inputs like music
2Power
If gain is increased to improve amplification, then audible output is improved, but feedback oscillation occurs more easily
Solution Approach 1:
The patent uses feedback mechanisms in two ways: first, the adaptive feedback canceller continuously monitors the feedback path and adjusts its compensation based on the actual feedback present; second, the synthesized signal is dynamically adjusted based on the audio input and feedback conditions. This dual feedback approach allows the system to operate at higher gains while maintaining stability by continuously adapting to changing feedback conditions
3Reliability
If advanced signal processing algorithms are used to reduce bias, then feedback compensation is improved, but device complexity increases
Solution Approach 1:
Instead of using complex non-linear processing or multiple parallel algorithms, the patent uses a copying approach where a simplified sound model is used to generate a synthesized signal. This synthesized signal is then added to the output to reduce bias. The sound model is a simplified representation that captures the essential acoustic characteristics without requiring complex processing, thus reducing device complexity while maintaining feedback compensation accuracy
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 enhances feedback compensation by allowing larger gain and improved dynamic performance without sacrificing speech intelligibility or sound quality, particularly for hearing-impaired individuals, with increased stable gain up to 10 dB and robustness against dynamic changes in the feedback path.
Implementation Method 1
a microphone for converting sound into an audio input signal
Implementation Method 2
a receiver for converting an audio output signal into an output sound signal
Data Source
AI summary
A hearing aid includes a microphone for converting sound into an audio input signal, a hearing loss processor, an adaptive feedback suppressor configured for generation of a feedback suppression signal by modelling a feedback signal path of the hearing aid, a subtractor coupled to an output of the adaptive feedback suppressor, wherein the subtractor is configured for subtracting the feedback suppression signal from the audio input signal, and outputting a feedback compensated audio signal to the hearing loss processor, and wherein the hearing loss processor is configured for processing the feedback compensated audio signal in accordance with a hearing loss of a user of the hearing aid, a synthesizer configured for generation of a synthesized signal based at least on a sound model and the audio input signal, and a receiver for generating an output sound signal based at least on the synthesized signal.