Acoustic Echo Cancellation Adaptation Rate Control
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Solution Overview
Problem
Acoustic echo cancellers (AECs) face challenges in maintaining effective echo cancellation due to conflicting adaptation strategies triggered by multiple detector modules, particularly in situations like double talk and echo path changes, leading to potential divergence and reduced performance.
Innovation Solution
Implementing a full system controller with a priority scheme to manage the adjustments triggered by various detector modules, including double-talk and echo path change detectors, to control the adaptation rate and coefficients of the AEC, ensuring consistent and optimal echo cancellation across different signal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the feedback loop continuously adjusts adaptation rate based on detector modules, then echo cancellation adapts to environmental changes, but conflicting detector strategies cause system instability and divergence
Solution Approach 1:
A priority scheme acts as an intermediary mechanism that mediates between conflicting detector modules. The priority scheme receives inputs from multiple detectors (double-talk detector, echo path change detector, etc.) and determines the appropriate adaptation rate by establishing a hierarchical priority structure, preventing direct conflict between opposing adaptation strategies.
Solution Approach 2:
The system dynamically changes the adaptation rate parameter based on detected signal conditions. By adjusting this key parameter according to priority-based detector outputs, the system adapts to different acoustic environments while maintaining stability through controlled parameter transitions rather than uncoordinated detector-driven changes.
2Measurement precision
If multiple detector modules are used to monitor signal conditions, then detection accuracy improves, but strategy conflicts increase and performance decreases
Solution Approach 1:
The detection function is segmented into specialized detector modules, each responsible for specific signal conditions (double-talk detection, echo path change detection, etc.). This segmentation allows precise detection of different conditions while the priority scheme integrates these segmented detection results into a unified adaptation strategy, preventing performance degradation from strategy conflicts.
Solution Approach 2:
The priority scheme serves as an intermediary that reconciles the outputs of multiple detector modules. It processes detection results from various specialized detectors and translates them into coordinated adaptation rate adjustments, ensuring that the combined detection accuracy of multiple modules translates into improved rather than degraded echo cancellation performance.
3Measurement precision
If adaptation rate is increased to respond to echo path changes, then echo estimation accuracy improves, but divergence risk increases during double talk
Solution Approach 1:
The adaptation rate is made dynamic rather than fixed, allowing the system to adjust the speed of coefficient updates based on current signal conditions. During echo path changes, the adaptation rate increases to improve echo estimation accuracy, while during double-talk conditions, the rate decreases to prevent divergence, creating a dynamic response that optimizes both accuracy and stability.
Solution Approach 2:
The priority scheme acts as an intermediary that receives inputs from both echo path change detectors and double-talk detectors, then determines the appropriate adaptation rate. This mediation ensures that the competing demands for high adaptation rate (from echo path change detection) and low adaptation rate (from double-talk detection) are resolved in a way that maintains both echo estimation accuracy and convergence stability.
Data Source
AI summary
An acoustic echo canceller (AEC) system may be configured to reset the coefficients of a transform equation when an estimated echo diverges from actual acoustic echo. Features are disclosed for determining when to reset the coefficients, and for enabling the reset operation to be performed reliably. Additional features are disclosed for detecting other signal conditions besides AEC divergence, for adjusting the rate at which the coefficients are adapted in response to such conditions, and for prioritizing between potentially incompatible adjustments.