Multilevel Filter Bank Tuning for Low-Delay Hearing Processing
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Solution Overview
Problem
Conventional multilevel filter banks in hearing devices face challenges in achieving minimal group delay and power consumption while maintaining effective aliasing interference reduction and sufficient channel bandwidth, particularly due to intensive sub-band processing and high amplification requirements.
Innovation Solution
A method to optimize the structure of a multilevel filter bank by varying the number of channels and oversampling factor, using a near-perfect reconstruction filter bank with complex modulated polyphase filter banks, and selecting parameters to minimize group delay and operation rate, resulting in a reduced parameter space for optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional multilevel filter banks are used with intensive sub-band processing and high amplification, then aliasing interference is reduced, but group delay increases and power consumption increases
Solution Approach 1:
The patent optimizes filter bank parameters including the number of channels (K), oversampling factor (OSF), and filter order (N) to achieve minimal group delay. Specifically, it determines optimal value pairs of K and OSF that satisfy the criterion of minimizing group delay while maintaining aliasing interference below 60 dB, thereby resolving the contradiction between aliasing reduction and group delay minimization.
Solution Approach 2:
The patent employs dynamic parameter selection where the filter bank structure (number of channels and oversampling factor) is optimized based on specific application requirements. The system dynamically adjusts between different filter bank configurations to balance aliasing suppression with group delay performance, rather than using a fixed conventional structure.
2Object-affected harmful factors
If conventional multilevel filter banks are used with intensive sub-band processing, then aliasing interference is reduced, but power consumption increases
Solution Approach 1:
The patent determines optimal values for the number of channels (K) and oversampling factor (OSF) that minimize the operation rate while maintaining aliasing interference below 60 dB. The optimization process evaluates multiple parameter combinations and selects those that reduce computational complexity and power consumption, directly addressing the contradiction between aliasing reduction and energy efficiency.
Solution Approach 2:
The patent extracts and eliminates unnecessary processing stages from conventional filter banks. By optimizing the number of channels and oversampling factor, it removes redundant computational operations while maintaining effective aliasing suppression, thereby reducing power consumption without sacrificing performance.
3Quantity of substance
If the number of channels is increased to meet minimum 22 channels requirement, then channel bandwidth coverage is improved, but device complexity increases
Solution Approach 1:
The patent optimizes the number of channels (K) as a variable parameter alongside the oversampling factor. Instead of fixed conventional structures, it determines optimal K values that achieve sufficient channel bandwidth coverage with minimal complexity. The optimization process identifies the minimum necessary number of channels to meet performance requirements, avoiding unnecessary complexity.
Solution Approach 2:
The patent creates a universal filter bank structure that can adapt to different channel requirements. By making the number of channels a variable parameter in the optimization process, the same filter bank design methodology can achieve different channel configurations (including the minimum 22 channels requirement) without requiring separate complex designs for each case.
4Object-affected harmful factors
If oversampling factor is increased to reduce aliasing, then aliasing interference is reduced, but operation rate increases and power consumption increases
Solution Approach 1:
The patent treats the oversampling factor (OSF) as a variable parameter to be optimized alongside the number of channels. The optimization process determines optimal OSF values that achieve aliasing interference below 60 dB while minimizing the operation rate. This resolves the contradiction by finding the minimal sufficient oversampling factor rather than using excessively high values.
Solution Approach 2:
The patent employs an optimization process that evaluates the relationship between oversampling factor and aliasing interference levels. By measuring the actual aliasing reduction achieved at different OSF values, the system provides feedback to select the minimal OSF that meets the 60 dB aliasing threshold, thereby avoiding unnecessary increases in operation rate and power consumption.
Data Source
AI summary
A filter bank system that is optimized with respect to group delay and power consumption is provided. The filter bank system has multiple levels and has an input-side and an output-side filter bank based on a defined filter type. The input-side filter bank has input channels as a variable first parameter, and an oversampling factor as a variable second parameter. For optimizing the multilevel filter bank, a group delay and an operation rate are now respectively determined for each of a plurality of value pairs of the first and second parameters. The value pair for which the associated group delay and the associated operation rate satisfy a defined criterion, in particular for which they are as low as possible, is selected from the value pairs. The input-side filter bank is subsequently configured with the number of channels and the oversampling factor corresponding to the selected value pair.