Hearing Aid Adaptive Filter Configuration for Zero Delay
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Solution Overview
Problem
Traditional hearing aid systems face challenges with processing delay and phase distortion, particularly when using filter banks with high frequency resolution, which can negatively impact speech intelligibility.
Innovation Solution
The implementation of an adaptive filter configuration that includes an all-pass filter and adaptive filters to optimize processing, ensuring zero delay and zero phase distortion, by using adaptive filter coefficients to predict signal components and minimize error, thereby canceling out delays and phase shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional filter banks with high frequency resolution are used, then frequency resolution is improved, but processing delay and phase distortion increase
Solution Approach 1:
The filter bank is divided into multiple sub-filter banks, each processing a specific frequency range. This segmentation allows parallel processing of different frequency components, reducing the overall processing delay while maintaining high frequency resolution through the combined output of all sub-filter banks.
Solution Approach 2:
The patent transforms the traditional single-dimension filter bank approach into a multi-dimensional structure by introducing both frequency dimension segmentation and time-domain parallel processing. This dimensional expansion enables simultaneous high frequency resolution and low processing delay through coordinated processing across multiple dimensions.
2Measurement precision
If traditional filter banks with high frequency resolution are used, then frequency resolution is improved, but phase distortion increases
Solution Approach 1:
The patent implements a feedback mechanism where the output of each sub-filter bank is processed through adaptive phase compensation filters that use the input signal as reference. This feedback loop continuously adjusts the phase response to minimize distortion while preserving the high frequency resolution achieved by the filter bank structure.
Solution Approach 2:
Phase compensation filters are introduced as intermediary components between the analysis filter bank and synthesis filter bank. These intermediary filters specifically address phase distortion by adjusting the phase of each frequency component without affecting the magnitude response, thereby preserving frequency resolution while eliminating phase distortion.
3Measurement precision
If filter banks are used for signal processing, then frequency resolution is improved, but device complexity increases
Solution Approach 1:
The patent designs the sub-filter banks to be identical in structure and parameters, allowing a single filter design to be reused multiple times across different frequency ranges. This universality reduces design complexity and computational overhead while maintaining high frequency resolution through the parallel operation of multiple identical filter units.
Solution Approach 2:
Instead of designing a single complex high-resolution filter bank, the patent uses multiple simpler filter banks with moderate resolution that operate in parallel. The collective output of these simpler filters achieves the equivalent of a single complex high-resolution filter, thereby reducing individual filter complexity while maintaining overall system resolution.
Data Source
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AI summary
A method of operating a hearing aid system with virtually zero delay and phase distortion. The invention also provides a hearing aid system (100) adapted for carrying out such a method.