Acoustic Echo Mitigation via Dynamic Residual Power Estimation
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Solution Overview
Problem
Existing acoustic echo mitigation techniques face challenges in robustly estimating residual echo power due to power changes caused by factors like noise, double talk, and echo path changes, often requiring hard threshold decisions that are not universally effective.
Innovation Solution
The proposed solution involves continuously tracking power changes in the error signal and using a soft decision mechanism to adaptively control the acoustic echo canceller, eliminating the need for hard thresholds by distinguishing between double talk, noise, and echo path changes through reliable estimations based on historical data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hard-decision voice activity detector with fixed threshold is used for double talk detection, then the system complexity is reduced, but the reliability of residual echo power estimation deteriorates due to inability to adapt to different scenarios
Solution Approach 1:
The patent applies dynamics by transitioning from a static hard-threshold voice activity detector to a dynamic soft-decision mechanism. The double talk detection is no longer based on a fixed threshold but on continuously updated statistics of the error signal, allowing the system to adapt to varying acoustic environments, noise levels, and echo path changes. This dynamic approach improves reliability while maintaining reasonable complexity through efficient statistical updates.
Solution Approach 2:
The patent implements feedback by continuously monitoring the error signal statistics and using this information to adjust the double talk detection threshold and residual echo power estimation. The system feeds back the observed error signal characteristics (mean, variance, minimum statistics) to continuously refine the detection mechanism, creating a closed-loop system that adapts to changing conditions rather than relying on pre-set fixed thresholds.
2Reliability
If soft decision mechanism with continuous tracking is used for power change adaptation, then the reliability of echo mitigation improves, but the device complexity increases due to continuous statistics updating
Solution Approach 1:
The patent applies preliminary action by pre-computing and maintaining statistical parameters (mean, variance, minimum statistics) of the error signal during normal operation. These statistics are continuously updated in the background, so when double talk or echo path changes occur, the system already has the necessary statistical information ready for rapid and reliable detection, avoiding the need for complex real-time computations during critical events.
Solution Approach 2:
The patent utilizes parameter changes by monitoring variations in error signal statistics (mean, variance, minimum statistics) to detect double talk and echo path changes. Instead of complex pattern recognition, the system tracks changes in these fundamental statistical parameters, which naturally reflect the state of the acoustic environment. This approach achieves high reliability through simple, efficient parameter monitoring and comparison.
3Measurement precision
If adaptive tracking of error signal power is used to distinguish double talk from echo path change, then the measurement precision of residual echo power estimation is improved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent applies dimensionality change by moving from single-dimensional power level detection to multi-dimensional statistical analysis. Instead of merely tracking the magnitude of error signal power, the system simultaneously monitors multiple statistical dimensions: mean, variance, and minimum statistics. This multi-dimensional approach provides richer information about the nature of power changes, enabling more precise distinction between double talk and echo path changes while maintaining manageable complexity through efficient statistical computations.
Data Source
AI summary
The present application provides an acoustic echo mitigation apparatus and method, an audio processing apparatus and a voice communication terminal. According to an embodiment, an acoustic echo mitigation apparatus is provided, including: an acoustic echo canceller for cancelling estimated acoustic echo from a microphone signal and outputting an error signal; a residual echo estimator for estimating residual echo power; and an acoustic echo suppressor for further suppressing residual echo and noise in the error signal based on the residual echo power and noise power. Here, the residual echo estimator is configured to be continuously adaptive to power change in the error signal. According to the embodiments of the present application, the acoustic echo mitigation apparatus and method can, at least, be well adaptive to the change of power of the error signal after the AEC processing, such as that caused by change of double-talk status, echo path properties, noise level and etc.