Adaptive Acoustic Echo Cancellation for Variable Channel Delays
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Solution Overview
Problem
Acoustic echo cancellation systems face performance issues due to sensitivity to differences in time alignment between speaker and microphone frame boundaries, leading to reduced echo suppression and degraded audio quality.
Innovation Solution
Implementing multiple acoustic echo cancellation modules with staggered delays and sub-band filters, such as WOLA filter-banks and STFT, to process input signals in parallel, and adaptively adjust filters based on predicted echo signals and microphone inputs to enhance echo reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single acoustic echo cancellation module is used, then the system structure is simple, but the echo suppression performance deteriorates when channel delay varies
Solution Approach 1:
The patent divides the echo cancellation system into multiple parallel modules, each processing the input signal with different delay values. This segmentation allows the system to handle varying channel delays more effectively, as each module can be optimized for specific delay conditions, thereby improving overall echo suppression performance without requiring a completely complex reconfiguration of the entire system.
Solution Approach 2:
The patent implements dynamic adaptation where the system can switch between different delay values in the multiple echo cancellation modules based on the actual channel conditions. This dynamic approach enables the system to maintain optimal echo suppression performance across varying channel delays while keeping the overall system structure manageable through automated adaptation rather than manual complexity management.
2Reliability
If multiple acoustic echo cancellation modules with different delays are used, then the echo suppression performance improves, but the device complexity increases
Solution Approach 1:
The patent combines multiple echo cancellation modules with different delay values into a unified parallel structure that processes signals simultaneously. By merging these modules and using signal combining techniques at the output, the system achieves improved echo suppression performance while managing the complexity through integrated processing rather than separate independent systems, reducing overall implementation complexity.
Solution Approach 2:
The patent varies the delay parameter across multiple echo cancellation modules to optimize performance for different channel conditions. This parameter change approach allows the system to handle a wider range of delay values without requiring proportional increases in system complexity, as the same basic module structure is reused with different delay settings rather than requiring fundamentally different processing approaches.
3Measurement precision
If adaptive filtering is applied to adjust filters based on predicted echo signals, then the echo reduction accuracy improves, but the computational requirements increase
Solution Approach 1:
The patent implements adaptive filtering with feedback mechanisms where the system continuously adjusts filter coefficients based on the difference between predicted and actual echo signals. This feedback approach improves echo reduction accuracy by allowing the system to learn from its own performance and optimize its filtering parameters in real-time, while the feedback structure provides a systematic way to manage computational requirements through targeted adjustments rather than brute-force computation.
Solution Approach 2:
The patent applies dynamic adaptation where the filtering parameters are adjusted in real-time based on the operating conditions and predicted echo signals. This dynamic approach allows the system to optimize computational efficiency by adjusting the degree of adaptation based on current needs, performing more complex computations only when necessary and using simpler processing when conditions permit, thereby managing the trade-off between accuracy and computational requirements.
Data Source
AI summary
Examples of the disclosure relate to acoustic echo cancellation using adaptive filtering modules. An apparatus for acoustic echo cancellation is configured to process a first input signal using a first acoustic echo cancellation module to obtain a first prediction signal and to process a second input signal using a second acoustic echo cancellation module to obtain a second prediction signal. The first input signal is based on a loudspeaker signal and the second input signal is a delayed first input signal. The prediction signals are processed to obtain a predicted echo signal. The predicted echo signal is applied to a received microphone signal to reduce echo from loudspeaker playback in the received microphone signal. The acoustic echo cancellation modules can be adapted using an adaptive filtering module.