Adaptive Leakage Factor Adjustment for Active Noise Reduction
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Solution Overview
Problem
Active noise reduction systems using adaptive filters and narrowband feed forward techniques face challenges in achieving complete noise elimination, as they typically only attenuate noise rather than completely reducing it to zero.
Innovation Solution
The method involves determining and smoothing leakage factors based on triggering conditions to modify filter coefficients for an adaptive filter, which is applied to an audio signal to produce an active noise reduction signal, allowing for recursive and repetitive operation to attenuate specific spectral components of noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive filters are used to reduce noise, then noise attenuation is achieved, but complete noise elimination is not possible and audible artifacts like clicks and distortions occur
Solution Approach 1:
The patent applies dynamics by making the leakage factor adjustable and adaptive rather than fixed. The system dynamically modifies the leakage factor based on system stability assessments and triggering conditions, allowing the filter to adapt its behavior to prevent audible artifacts while maintaining noise attenuation effectiveness.
Solution Approach 2:
The patent changes the parameter of the leakage factor from a fixed value to a variable parameter that can be modified based on system conditions. By adjusting the leakage factor parameter in response to triggering conditions and stability assessments, the system optimizes the balance between noise reduction and artifact prevention.
2Object-affected harmful factors
If leakage factors are adjusted to improve noise reduction, then noise attenuation improves, but system stability may be compromised
Solution Approach 1:
The patent implements feedback by continuously assessing system stability and using this information to trigger adjustments to the leakage factor. The system monitors its own performance and stability, then feeds this information back to modify the leakage factor accordingly, creating a closed-loop control system that balances noise attenuation with stability.
Solution Approach 2:
The system dynamically adjusts the leakage factor based on real-time stability assessments. Rather than using a static leakage factor, the system makes the leakage factor adaptable and responsive to changing conditions, allowing it to optimize noise reduction while maintaining stability.
3Object-affected harmful factors
If filter coefficients are modified using leakage factors, then noise reduction performance improves, but complexity of the system increases
Solution Approach 1:
The patent applies partial action by implementing leakage factor adjustment only under specific triggering conditions rather than continuously. The system selectively modifies filter coefficients based on assessed stability and triggering events, avoiding unnecessary complexity while maintaining improved noise reduction performance where needed.
Data Source
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AI summary
A method for determining leakage factors or adaptation rates, or both, for adaptive filters in an active noise reduction system. The leakage factor or adaptation rate, or both, may vary depending on a parameter of an input reference signal. The parameter may include one or more of reference signal input frequency, rate of change of reference input signal frequency, if a predetermined triggering condition exits, or if a predetermined event has occurred.