Microphone Signal Processing for Smoother AEC Artifact Suppression
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Solution Overview
Problem
Existing acoustic echo cancellation (AEC) methods in microphone systems produce unwanted artefacts due to poor adaptive filter performance and abrupt changes in sound paths, especially when separate audio capture and output devices are used, leading to disturbing audible fluctuations.
Innovation Solution
Implementing controlled ambient noise suppression processing in conjunction with AEC, where the level of ambient noise suppression is gradually increased and decreased in response to AEC being enabled, with adjustments based on frequency ranges and trigger events to mitigate artefacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic echo cancellation (AEC) processing is enabled to cancel echo, then echo cancellation performance is improved, but unwanted artefacts and audible fluctuations increase due to poor adaptive filter performance and abrupt changes in sound paths
Solution Approach 1:
The patent introduces ambient noise suppression processing as an intermediary step between AEC processing and the final output signal. This intermediate processing stage suppresses artefacts generated by AEC before they reach the final output, effectively mediating between the echo cancellation function and the harmful artefacts it produces.
Solution Approach 2:
The patent dynamically adjusts the level of ambient noise suppression based on whether AEC is active. When AEC is enabled, the ambient noise suppression level is increased to counteract the artefacts. This parameter change approach allows the system to adapt its processing characteristics based on the operational state, resolving the contradiction between echo cancellation effectiveness and artefact generation.
2Object-generated harmful factors
If the level of ambient noise suppression is increased to reduce artefacts, then artefact perception is reduced, but abrupt changes in ambient audio levels may still occur
Solution Approach 1:
The patent implements dynamic control of ambient noise suppression levels based on the operational state of AEC processing. The system transitions smoothly between different suppression levels as AEC is enabled or disabled, allowing the ambient audio characteristics to adapt dynamically while maintaining stability through controlled transitions rather than abrupt changes.
Solution Approach 2:
The system monitors the state of AEC processing and uses this feedback to adjust the ambient noise suppression level accordingly. When AEC is detected as active, the feedback mechanism triggers an increase in ambient noise suppression to counteract artefacts, creating a closed-loop control system that maintains audio quality stability.
Data Source
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AI summary
Various example embodiments relate to microphone signal processing. For example, a method is disclosed comprising enabling acoustic echo cancellation, AEC, processing on at least one captured microphone signal in response to a trigger event, wherein the AEC processing is performed for a first time period for providing at least one post-processed captured microphone signal. The method may also comprise applying ambient noise suppression processing on the at least one post-processed captured microphone signal, wherein a level of ambient noise suppression applied on the at least one post-processed captured microphone signal is increased from a first level to one or more second levels in response to AEC processing being enabled.