Subband Acoustic Echo Cancellation With Regularized Correlation Matrices
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Solution Overview
Problem
Current acoustic echo cancellation techniques for spatial audio communication and teleconferencing on mobile devices face challenges due to high complexity and poor performance in handling multi-channel and stereo playback, particularly with long echo impulse responses and varying playback conditions.
Innovation Solution
Implementing subband adaptive filters with diagonally regularized correlation matrices to iteratively determine gain vectors and update filter coefficients, using a technique that ensures robustness and reduced computational complexity by diagonal regularization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-domain filter implementations are used for acoustic echo cancellation, then filtering capability is achieved, but computational complexity becomes high due to long echo impulse responses requiring thousands of taps
Solution Approach 1:
The patent divides the time-domain filtering operation into multiple frequency subbands. Each subband is processed independently with fewer filter taps, and the results are combined through inverse Fourier transform. This segmentation reduces the computational complexity from requiring thousands of taps in time-domain to manageable complexity in frequency-domain subbands.
Solution Approach 2:
The patent replaces the mechanical time-domain filtering approach with a frequency-domain processing system using Fast Fourier Transform. Instead of directly filtering in time-domain with long impulse responses, the system transforms signals to frequency-domain, applies filtering operations there, and transforms back, substituting complex time-domain mechanics with more efficient frequency-domain operations.
2Adaptability or versatility
If multiple adaptive filters are applied in parallel to every frequency bin, then multi-channel echo cancellation is achieved, but computational complexity increases significantly
Solution Approach 1:
The patent merges the processing of multiple channels and multiple frequency bins into a unified frequency-domain framework. Instead of independently processing each channel and frequency bin with separate adaptive filters, the system processes all subbands simultaneously in frequency-domain, sharing computational resources and reducing overall complexity while maintaining multi-channel capability.
3Reliability
If conventional AEC algorithms are used on mobile devices, then echo cancellation is provided, but battery consumption and device heating increase due to high CPU usage
Solution Approach 1:
The patent changes the fundamental parameters of the AEC algorithm by moving from time-domain to frequency-domain processing. This parameter change in the processing domain enables more efficient computation that reduces CPU usage, thereby lowering battery consumption and device heating while maintaining echo cancellation performance on mobile devices.
Data Source
AI summary
A system for acoustic echo cancellation comprising, obtaining on one or more near-end microphone signals and one or more playback signals, obtaining one or more subband signal sequences based on the one or more playback signals, processing the obtained one or more subband signal sequences with one or more subband adaptive filters, and reducing an echo in the obtained microphone signal via using outputs from the one or more subband adaptive filters.