Microphone Echo Cancellation With Adaptive Noise 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 audible feedback and fluctuations in ambient audio levels.
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 feedback are generated due to poor adaptive filter performance and abrupt changes in sound paths
Solution Approach 1:
The patent applies dynamics by making the ambient noise suppression level adjustable and adaptive rather than fixed. The system dynamically adjusts the suppression level based on whether AEC is enabled, transitioning between different operational states to optimize performance and minimize artefacts under varying conditions
Solution Approach 2:
The patent changes the parameter of ambient noise suppression level from a static value to a conditional variable that takes different values based on AEC state. When AEC is enabled, the suppression level is increased to compensate for artefacts; when AEC is disabled, the suppression level is decreased to maintain natural audio quality
2Object-generated harmful factors
If the level of ambient noise suppression is increased to compensate for AEC artefacts, then artefact reduction is improved, but abrupt changes in audio levels occur causing unnatural listening experience
Solution Approach 1:
The patent applies preliminary anti-action by proactively adjusting the ambient noise suppression level in response to AEC enablement. The system anticipates the generation of artefacts when AEC is enabled and pre-compensates by increasing suppression, rather than reacting after artefacts are generated
Solution Approach 2:
The system uses feedback by monitoring the AEC enable state and using this information to adjust the ambient noise suppression level. The AEC state serves as feedback input that triggers corresponding changes in suppression intensity, creating a closed-loop control system
3Ease of operation
If separate audio capture and output devices are used to improve portability and user experience, then ease of operation is improved, but sound path changes become more abrupt leading to worse echo cancellation performance
Solution Approach 1:
The patent makes the audio processing system dynamic by enabling it to adapt its behavior based on the operational state. The ambient noise suppression level dynamically adjusts in response to AEC enablement, allowing the system to optimize for artefact reduction when separate devices are used with AEC enabled
Data Source
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.