Acoustic Echo Cancellation With Adaptive Post-Filter Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acoustic echo cancellation systems face challenges in effectively handling double talk situations and residual echoes, particularly in environments with non-linearities, leading to suboptimal performance and unwanted artifacts.
Innovation Solution
A system and method that incorporates an adaptive filter with a controlled adaptation step size, evaluated through statistical analysis, and an adaptive post-filter with minimum damping, to approximate unknown transfer functions and suppress echoes, while using a filter control block to manage the adaptation step size and post-filter transfer function based on system distance and signal energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the adaptation step size is increased to improve convergence speed, then the echo cancellation performance improves, but stability deteriorates in double talk situations
Solution Approach 1:
The patent implements dynamic adaptation by making the adaptation step size variable rather than fixed. The step size is adjusted based on the system distance metric and double-talk detection, allowing the system to achieve fast convergence when appropriate while maintaining stability during double-talk situations. This is achieved through the filter control block that modifies the adaptation step size based on statistical analysis of system distance.
Solution Approach 2:
The patent changes the parameter of adaptation step size from a constant value to a dynamically adjusted parameter. By modifying this critical parameter based on system conditions (system distance and double-talk detection), the system optimizes both convergence speed and stability performance according to the current operational state.
2Reliability
If aggressive echo suppression is applied to reduce residual echoes, then echo cancellation performance improves, but unwanted artifacts are introduced
Solution Approach 1:
The patent employs feedback mechanisms through the filter control block that continuously monitors system distance and double-talk conditions. This feedback allows the system to adjust the post-filter damping dynamically, applying stronger suppression when echoes are present and reducing suppression when speech is detected, thereby preventing artifact generation while maintaining echo cancellation effectiveness.
Solution Approach 2:
The system dynamically adjusts the post-filter damping parameter based on real-time analysis of system distance and double-talk detection. This dynamic adjustment enables the system to optimize the balance between echo suppression and artifact prevention, applying the appropriate level of filtering based on current acoustic conditions.
3Device complexity
If fixed post-filter damping is used to simplify implementation, then device complexity is reduced, but adaptability to different acoustic environments deteriorates
Solution Approach 1:
The system implements self-service by automatically adapting the post-filter damping based on statistical analysis of system distance and double-talk detection. The filter control block enables the system to self-adjust to different acoustic environments without requiring manual configuration or complex external control, achieving environmental adaptability through autonomous parameter adjustment based on observed acoustic conditions.
Data Source
Figure 1~4
Figure 2
Figure 5~6
AI summary
Canceling acoustic echoes includes picking up with a microphone sound generated by a sound source and transferred from the sound source to the microphone via an unknown transfer path having an unknown transfer function, and providing an electrical microphone signal therefrom. It further includes approximating the unknown transfer function with an estimated transfer function of an adaptive filter and filtering an electrical signal representative of the sound generated by the sound source with the estimated transfer function to provide an estimated signal therefrom, the adaptive filter having an adaptive adaptation step size. It further includes filtering a difference signal, which is the difference between the microphone signal and the estimated signal, with a post filter transfer function of an adaptive post filter. The post filter transfer function is the difference between one and the adaptive adaptation step size, and the adaptive post filter is configured to have a minimum damping, the minimum damping being limited to a minimum threshold.