Multichannel Acoustic Echo Cancellation with Unique Channel Estimations
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Solution Overview
Problem
Multichannel acoustic echo cancellation systems face challenges in accurately updating estimated transfer functions due to the non-uniqueness problem when signals sent to speakers are perfectly correlated, leading to inaccurate echo cancellation and intermittent results.
Innovation Solution
A multi-channel echo cancellation system that dynamically adapts to changes in acoustic conditions by using secondary adaptive filters to adjust cancellation based on decorrelated reference signals, even if initial signals are highly correlated, and employs a controller to manage the adaptation process, including decorrelation techniques and Fourier transforms to track coherence variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional AEC systems use single shared adaptive filter for multiple channels, then device complexity is reduced, but measurement precision of transfer functions deteriorates due to non-uniqueness problem with correlated signals
Solution Approach 1:
The patent divides the single shared adaptive filter into multiple separate adaptive filters, with each channel having its own dedicated adaptive filter. This segmentation allows each filter to independently estimate the transfer function for its specific channel, eliminating the non-uniqueness problem that occurs when a single filter must serve multiple correlated channels. The result is improved measurement precision without significantly increasing overall system complexity.
2Measurement precision
If AEC systems use individual channel estimations for each speaker-microphone coupling, then measurement precision improves, but device complexity increases due to multiple adaptive filters
Solution Approach 1:
The patent implements a universal adaptive filter architecture where each adaptive filter serves multiple functions: it estimates the transfer function for its specific speaker-microphone coupling, enables independent channel processing, and works within a unified multichannel AEC framework. This multi-functionality justifies the increased number of filters by demonstrating that each filter provides unique value for its specific channel estimation task.
3Device complexity
If traditional systems assume single impulse response for all speakers, then device complexity is minimized, but reliability of echo cancellation deteriorates in dynamic acoustic environments
Solution Approach 1:
The patent transitions from a static acoustic model that assumes a single impulse response for all speakers to a dynamic model where each speaker has its own time-varying impulse response. This allows the system to adapt to changes in the acoustic environment, such as moving objects or changing room conditions, thereby maintaining reliable echo cancellation performance in dynamic settings.
Data Source
AI summary
A multi-channel echo cancellation system that dynamically adapts to changes in acoustic conditions. The system does not require a sequence of “start-up” tones to determine the impulse responses. Rather, the adaptive filters approximate estimated transfer functions for each channel. A secondary adaptive filter adjusts cancellation to adapt to changes in the actual transfer functions over time after the adaptive filters have been trained, even if the reference signals are not unique relative to each other.