Adaptive Beamforming for Echo Cancellation in Multi-Channel Audio
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Solution Overview
Problem
Conventional Acoustic Echo Cancellation (AEC) systems face challenges in stereo and multi-channel audio systems with wireless or network-connected loudspeakers and microphones due to differences in signal synchronization, compression/decompression, non-linear post-processing, and buffering, which affect the accuracy of echo removal.
Innovation Solution
The system employs adaptive beamforming techniques to determine a target signal and a reference signal based on audio beamforming, using fixed and adaptive beamformers to isolate speech by removing the reference signal from the target signal, thereby isolating speech from reproduced sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AEC systems use simple signal subtraction for echo removal, then the system complexity is low, but the echo cancellation accuracy deteriorates in multi-channel wireless audio systems
Solution Approach 1:
The patent segments the audio signal processing into multiple independent channels, each with its own beamforming and echo cancellation processing. The multi-channel system processes each channel separately through adaptive beamformers before combining results, allowing complex processing to be divided into manageable segments that maintain high accuracy without overwhelming system complexity
Solution Approach 2:
The patent introduces adaptive beamformers as intermediary components between the raw multi-channel audio signals and the final echo cancellation output. These beamformers act as mediators that separate desired speech signals from unwanted echo and noise components before the subtraction process, significantly improving cancellation accuracy while keeping the overall system architecture manageable
2Measurement precision
If the system processes all audio channels equally, then the processing is simple, but the signal-to-noise ratio deteriorates in complex audio environments
Solution Approach 1:
The patent applies different processing qualities to different spatial locations and signal sources. The adaptive beamformers create directionally-selective processing zones, applying enhanced processing to signals from specific directions (where speech is located) while using simpler processing for other channels. This local differentiation of processing quality improves overall signal-to-noise ratio without uniformly increasing processing complexity across all channels
3Measurement precision
If conventional AEC subtracts delayed reference signal directly, then the processing speed is fast, but the speech isolation accuracy deteriorates due to synchronization issues
Solution Approach 1:
The patent performs preliminary beamforming processing on all audio channels before the echo cancellation subtraction step. The adaptive beamformers pre-separate and align speech signals from different directions, creating synchronized, directionally-filtered inputs for the subtraction process. This preliminary action ensures that when subtraction occurs, the signals are already optimally aligned, maintaining both high speech isolation accuracy and processing speed
Data Source
AI summary
An echo cancellation system that performs audio beamforming to separate audio input into multiple directions and determines a target signal and a reference signal from the multiple directions. For example, the system may detect a strong signal associated with a speaker and select the strong signal as a reference signal, selecting another direction as a target signal. The system may determine a speech position and may select the speech position as a target signal and an opposite direction as a reference signal. The system may create pairwise combinations of opposite directions, with an individual direction being selected as a target signal and a reference signal. The system may select a fixed beamformer output for the target signal and an adaptive beamformer output for the reference signal, or vice versa. The system may remove the reference signal (e.g., audio output by the loudspeaker) to isolate speech included in the target signal.