Dynamic Non-Linear Processor Threshold for Acoustic Echo Cancellation
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Solution Overview
Problem
Existing acoustic echo cancellation systems struggle to effectively suppress residual echo during conferencing sessions, particularly in environments where the microphone is close to the loudspeaker, leading to poor audio quality.
Innovation Solution
The system automatically adjusts the threshold of a non-linear processor in an acoustic echo cancellation system by calculating the maximum value of a ratio between the microphone signal and the filtered remote audio signal, and setting the threshold accordingly based on whether the conferencing session is in a far end single talk or doubletalk condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed threshold is used in the non-linear processor, then the device complexity is reduced, but the echo suppression performance deteriorates in different conferencing conditions
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed threshold to a dynamic threshold that automatically adjusts based on the detected conferencing condition (FEST or doubletalk). The threshold is modified in real-time according to the ratio of microphone signal level to filtered remote audio signal level, allowing the system to adapt to different acoustic environments and talker conditions without increasing structural complexity
Solution Approach 2:
The patent changes the threshold parameter of the non-linear processor based on the conferencing condition. During FEST conditions, the threshold is set to a higher value (maximum ratio plus offset) to maximize echo suppression, while during doubletalk conditions, the threshold is reduced to preserve speech quality. This parameter adjustment resolves the contradiction by optimizing performance for each condition separately
2Reliability
If echo suppression is increased during FEST conditions, then audio quality is improved, but speech intelligibility may deteriorate during doubletalk conditions
Solution Approach 1:
The patent dynamically changes the threshold parameter based on the conferencing condition to optimize the trade-off between echo suppression and speech preservation. During FEST conditions, a higher threshold provides stronger echo suppression for better audio quality. During doubletalk conditions, the threshold is lowered to prevent suppression of actual speech, thereby maintaining speech intelligibility
Solution Approach 2:
The system uses feedback from the microphone signal and filtered remote audio signal to detect the conferencing condition and automatically adjust the threshold. The ratio calculation and condition detection provide continuous feedback that drives the threshold adjustment, ensuring optimal performance without manual intervention
Data Source
AI summary
Acoustic echo cancellation systems and methods are provided that can automatically adjust a threshold of a non-linear processor based on the state of a conferencing session, such as a far end single talk condition or a doubletalk condition. The state of the conferencing session may be detected based on various combinations of metrics that are measured from a microphone signal and a remote audio signal. The systems and methods can improve the removal of residual echo and therefore enhance the overall performance of the acoustic echo cancellation system.