Multichannel Acoustic Echo Cancellation with Adaptive Reference Selection
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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, non-linear post-processing, and buffering, leading to ineffective echo removal.
Innovation Solution
The implementation of an Adaptive Reference Signal Selection Algorithm (ARSSA) that performs audio beamforming to determine a reference signal and a target signal, combining it with a conventional AEC system using a playback reference signal to generate a combined reference signal, applying filters to enhance echo cancellation performance across various frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AEC systems are used in multi-channel audio systems with wireless loudspeakers, then the system structure is simple, but echo cancellation effectiveness deteriorates due to signal synchronization differences, compression, non-linear post-processing, and buffering
Solution Approach 1:
The patent divides the echo cancellation task into multiple independent AEC circuits, each handling a specific channel or signal path. Each circuit processes its own reference signal and microphone input separately, allowing parallel processing without interference. This segmentation enables the system to handle multi-channel audio while maintaining cancellation effectiveness for each individual channel.
Solution Approach 2:
The system dynamically selects between different AEC circuits based on real-time signal quality and system conditions. An output selector chooses the best cancellation result from multiple circuits, adapting to changing acoustic environments, wireless signal conditions, and non-linear distortions. This dynamic selection optimizes echo cancellation effectiveness without requiring a fixed complex architecture.
2Reliability
If multiple AEC circuits are implemented to handle different signal paths, then echo cancellation effectiveness improves, but device complexity increases
Solution Approach 1:
Multiple AEC circuits are designed with identical universal functionality, each capable of processing any channel or signal path. This multi-functionality allows the system to handle various audio configurations (stereo, surround, wireless) using the same basic circuit architecture, reducing the need for specialized complex designs for each scenario.
Solution Approach 2:
The patent uses identical copies of the AEC circuit design for different signal paths. Each circuit is a replicated instance of the same processing architecture, ensuring consistent performance across channels while simplifying implementation through reuse of proven design elements rather than creating unique complex solutions for each path.
3Adaptability or versatility
If dynamic selection between conventional and ARSSA-based echo cancellation methods is implemented, then adaptability to different system conditions improves, but processing complexity increases
Solution Approach 1:
The system continuously monitors signal characteristics and system conditions, using this feedback to dynamically select the most appropriate AEC circuit or processing method. Based on detected linearity, signal quality, and acoustic conditions, the output selector adapts in real-time, choosing between conventional and ARSSA-based approaches without requiring manual configuration or complex decision logic.
Data Source
AI summary
An echo cancellation system performs audio beamforming to separate audio input into multiple directions (e.g., target signals) and generates multiple audio outputs using two acoustic echo cancellation (AEC) circuits. A first AEC removes a playback reference signal (generated from a signal sent a loudspeaker) to isolate speech included in the target signals. A second AEC removes an adaptive reference signal (generated from microphone inputs corresponding to audio received from the loudspeaker) to isolate speech included in the target signals. A beam selector receives the multiple audio outputs and selects the first AEC or the second AEC based on a linearity of the system. When linear (e.g., no distortion or variable delay between microphone input and playback signal), the beam selector selects an output from the first AEC based on signal to noise (SNR) ratios. When nonlinear, the beam selector selects an output from the second AEC.