Equalization Filter for Hearing Device Signal Quality
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Solution Overview
Problem
Multi-stage filter bank systems in hearing devices cause disruptions in signal quality due to group delay differences between sub-band signals of varying bandwidths, leading to jumps in total signal delay.
Innovation Solution
Incorporating an equalization filter within the filter bank system to compensate for frequency response differences and group delays between filter bank channels, ensuring smooth transitions and minimizing disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-stage filter bank systems are used to process signals in hearing devices, then signal processing capability is improved, but group delay differences between sub-band signals cause disruptions in signal quality
Solution Approach 1:
The patent applies parameter changes by introducing an equalization filter that modifies the frequency response parameters of individual filter bank channels. This filter adjusts the group delay and magnitude response of each channel to match a reference channel, thereby compensating for the parameter variations that cause signal quality disruptions while preserving the multi-stage filter bank's signal processing capability
2Adaptability or versatility
If filter bank channels have different bandwidths to meet individual needs, then adaptability is improved, but jumps in total signal delay occur
Solution Approach 1:
The equalization filter changes the delay parameter of each filter bank channel by adjusting its frequency response. This allows channels with different bandwidths to have their group delays equalized to a reference value, eliminating delay jumps while preserving the adaptable bandwidth structure needed to meet individual hearing requirements
3Reliability
If correction unit delays subband signals to correct group delay times, then hearing deviation compensation is improved, but frequency response discontinuities remain
Solution Approach 1:
The equalization filter applies parameter changes to the frequency response of each filter bank channel, specifically adjusting both the group delay and magnitude response parameters. This comprehensive parameter adjustment not only compensates for hearing deviations through delay correction but also ensures frequency response continuity by matching the reference channel's characteristics, thereby resolving the discontinuities that remain after simple delay correction
Data Source
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AI summary
The device has a filter bank system with a multi-layer analysis filter bank (AFB) and a multi-stage synthesis filter bank (SFB) to separate an input signal of the hearing apparatus into multiple sub-band signals by a set of filter bank channels and/or to again merge the sub-band signals. The filter bank system has an equalization filter (EQ) to compensate differences of complex frequency responses between the filter bank channels. The equalization filter compensates damping or amplification differences and group delay differences between the filter bank channels.