Acoustic Echo Cancellation with Selective Post-Processing
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Solution Overview
Problem
Existing acoustic echo cancellation devices fail to effectively suppress echoes in hands-free mode, especially in double-talk situations where far-end speech and near-end speech or music signals are simultaneously present, leading to signal distortions due to the loudness of far-end signals.
Innovation Solution
An acoustic echo cancellation device that combines multiple input signals into an aggregate signal, uses adaptive filters to produce echo cancellation signals, and employs a post-processor to selectively suppress echo components, prioritizing suppression of echo components from one input signal over another, thereby minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a post-processor is used to suppress remaining echo components in the residual signal, then echo suppression is improved, but near-end signal distortion increases in double-talk situations
Solution Approach 1:
The patent segments the echo cancellation process into multiple independent adaptive filters, each processing a specific input signal (far-end speech, music, etc.) separately. The post-processor then receives multiple echo cancellation signals corresponding to different input sources, allowing selective suppression of echo components from dominant signals while preserving near-end speech, thus resolving the contradiction between echo suppression and signal distortion.
2Ease of operation
If the loudspeaker and microphone are positioned close together for hands-free mode, then ease of operation is improved, but echo cancellation performance deteriorates
Solution Approach 1:
The patent implements a multi-functional adaptive filter system that can process multiple types of input signals (far-end speech, music, etc.) simultaneously through separate adaptive filters. This universal approach allows the system to maintain effective echo cancellation performance regardless of the specific signal sources, enabling reliable hands-free operation even when the loudspeaker and microphone are positioned close together.
3Adaptability or versatility
If multiple input signals (far-end speech and music) are processed simultaneously, then adaptability is improved, but echo cancellation accuracy deteriorates
Solution Approach 1:
The patent divides the echo cancellation process into separate adaptive filters for different input signals (far-end speech, music, etc.), with each filter independently modeling its specific acoustic path. This segmentation maintains high echo cancellation accuracy for each signal type while preserving the system's ability to handle multiple simultaneous inputs, thus resolving the contradiction between adaptability and accuracy.
Data Source
AI summary
An acoustic echo cancellation device for canceling an echo in a microphone signal in response to first and second input signals includes a first combination unit for combining the first and second input signals into an aggregate input signal. The device further includes an adaptive filter unit for filtering the aggregate input signal so as to produce an aggregate echo cancellation signal. A second combination unit combines the aggregate echo cancellation signal with the microphone signal so as to produce a residual signal, and an additional filter unit filters either the first or second input signal so as to produce a first or a second partial echo cancellation signal. A post-processor unit suppresses remaining echo components in the residual signal. The post-processor unit uses at least one partial echo cancellation signal to suppress echo components corresponding with the first input signal to a greater extent than echo components corresponding with the second input signal.