Semi-Adaptive Audio Controller with Fixed and Adaptive ANR Filters
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Solution Overview
Problem
Existing ANC/ANR headphones struggle to maintain robust noise reduction performance in dynamic environments due to the limitations of fixed filters and the instability of adaptive filters, leading to degraded performance from sudden changes in noise direction or type.
Innovation Solution
A semi-adaptive ANC/ANR device that combines fixed and adaptive filters using an interactively updated weighting factor to generate improved anti-noise signals, ensuring high attenuation performance and stability by adjusting the weighting based on real-time performance comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adaptive ANC/ANR filters are used to adaptively compensate noises in dynamic environments, then the noise reduction performance is improved, but large estimation errors are caused by sudden changes in noise direction or type, degrading robustness
Solution Approach 1:
The patent combines fixed and adaptive filters into a hybrid architecture where the fixed filter provides stable baseline performance while the adaptive filter dynamically adjusts to environmental changes. This merging allows the system to achieve both high noise reduction performance and robustness against sudden changes.
Solution Approach 2:
The patent dynamically changes the weighting parameter between fixed and adaptive filter outputs based on performance monitoring. When the adaptive filter performs well, its weight is increased; when estimation errors occur, the weight is reduced, thus adapting the system behavior to maintain robustness while maximizing performance.
2Reliability
If fixed ANC/ANR filters are used, then robustness is maintained, but the system cannot adapt to changes in dynamic environments, resulting in degraded noise reduction performance
Solution Approach 1:
The patent merges fixed and adaptive filters in a parallel structure, allowing the fixed filter to maintain robustness while the adaptive filter provides environmental adaptation. The combination enables the system to benefit from both approaches simultaneously.
Solution Approach 2:
The patent introduces dynamic weighting control that adjusts the contribution of the adaptive filter based on real-time performance evaluation. This dynamic adjustment allows the system to transition between relying on the fixed filter (for robustness) and the adaptive filter (for performance) based on current environmental conditions.
3Adaptability or versatility
If a hybrid ANC/ANR system combining fixed and adaptive filters is used, then both robustness and adaptability are achieved, but the device complexity increases
Solution Approach 1:
The patent combines fixed and adaptive filters in a unified hybrid architecture with shared signal paths where possible. This merging approach achieves both robustness and adaptability while minimizing the increase in complexity through efficient resource sharing between filter components.
Solution Approach 2:
The patent implements a feedback mechanism that monitors the performance of the adaptive filter and automatically adjusts the weighting between fixed and adaptive components. This feedback control simplifies the overall system management by using automated performance-based adjustment rather than complex manual tuning or multiple switching mechanisms.
Data Source
AI summary
An audio controller for an active noise reduction, ANR, reduces an ambient noise signal. The audio controller includes processing circuitry configured to provide a fixed ANR filter configured to generate a first noise reduction signal. Moreover, the processing circuitry is further configured to provide an adaptive ANR filter. The adaptive ANR filter includes one or more adjustable filter coefficients for adapting the adaptive ANR filter and the adaptive ANR filter is configured to generate a second noise reduction signal. The processing circuitry is further configured to generate a total noise reduction signal as an adjustable weighted linear combination of the first noise reduction signal and the second noise reduction signal.